On the first question, it says my answer is wrong and I got 18 as my answer.

At first i got that too, but then i realized there was a -6 at the end of the problem. So the actual answer was 12. :)

i dont get the 2nd q how do we solve it when its an fraction

a fraction is division. so 10 divided by 5 can be written as a fraction 10/5, and x/y means x divided by y. does that help? you would do it along with multiplication in the order of operations.

how do you expand and simplify: 2(x- 1)(x+1)+(2x-1)(2x-1)

First distribute 3x over (2x+5) and then distribute -2x over (x-6): 3x(2x+5) - 2x(x-6) = 6x^2 + 15x - 2x^2 + 12x [Note: -2x * -6 = +12x, not -12x] = 6x^2 - 2x^2 + 15x + 12x [Rewrite with like terms in order.] = 4x^2 + 27x

I still don’t get 5 * y - x/y when x= 4 and y=2

First things first the question above is 5x - x/y You copied it wrong Even if you want the answer, here you go Your question is- 5 * y - x/y Let's substitute-5 * 4 - 4/2 Which gives us 5 * 4 - 2 20 - 2 = 8 Hope that helped

how can i find the answer in the equation 5x - x/y when x=4 and y =2

1) Substitute each value into the expression for their respective variable `5(4) - 4/2` 2) Follow PEMDAS -- Multiply: `20 - 4/2` -- Divide: `20 - 2` -- Subtract: `18` Hope this helps.

How come when evaluating expressions with two variables (the previous section) that the minus was completed prior to the plus. The questions was xy - y + 3x where x = 3 and y =2. BOMDAS 3 x 2 - 2 + 3 x 3 = 6 - 2 + 9 6 - 11

xy-y+3x , if x=3 and y=2 results to 6 - 2 + 9 = 13. Either a parenthesis in the exercise got lost or the solution is wrong, but for the given expression the above result is the correct solution.

Please help me understand answer from video demonstration xy-y+3x, where x = 3 and y = 2 3(2)-2+3(3) 6-2+9 The answer is given as 13 Why isn't it 6-(2+9)= -5

Because that is not a way to group. Both 6 and 9 are positive and 2 is negative, so you could associate (6+9)-2, but not as you show which makes the 0 negative on distribution

how would i do 5x-x/y when x is 4 and y is 2

First, we need to plug the numbers into the expression. So, 5x-x/y becomes 5 x 4 - 4/2. Next, we need to follow PEMDAS, so we need to do the multiplication and division first. Then, this expression becomes 20 - 2. And the result is 18. I hope it helps.

What is the 6a+4b-6 whan a = 1 and b=3 I'm Don't know how to do

Just plug in the values of a and b. 6a + 4b - 6 becomes: 6(1) + 4(3) - 6 or (6 * 1) + (4 * 3) - 6, You'll get 6 + 12 - 6. Use PEMDAS to find that addition comes first. So you can rewrite it as (6 + 12) - 6 which is 18 - 6. Your final answer should be 12.

Main content

Algebra 1

Course: Algebra 1 > Unit 1

Lesson 3: Substitution and evaluating expressions

Evaluating expressions with two variables

CCSS.Math:

6.EE.A.2

6.EE.A.2c

Google Classroom

We've already evaluated expressions with one variable. Now it's time to do it with two variables.

Khan Academy video wrapper

Evaluating expressions with two variablesSee video transcript

How to evaluate an expression with two variables

Let's say we want to evaluate the expression 10, plus, 2, p, minus, 3, r. Well, first we need to know the values of p and r. For example, to evaluate the expression when start color #11accd, p, equals, 4, end color #11accd and start color #e07d10, r, equals, 5, end color #e07d10, we just replace start color #11accd, p, end color #11accd with start color #11accd, 4, end color #11accd and start color #e07d10, r, end color #e07d10 with start color #e07d10, 5, end color #e07d10:

empty space, 10, plus, 2, start color #11accd, p, end color #11accd, minus, 3, start color #e07d10, r, end color #e07d10

equals, 10, plus, 2, dot, start color #11accd, 4, end color #11accd, minus, 3, dot, start color #e07d10, 5, end color #e07d10

equals, 10, plus, 8, minus, 15

equals, 3

So, the expression 10, plus, 2, p, minus, 3, r equals 3 when p, equals, 4 and r, equals, 5.

Now, let's practice

Problem 1

Current

Evaluate 6, a, plus, 4, b, minus, 6 when a, equals, 1 and b, equals, 3.

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hrhsimonn
Posted 6 years ago. Direct link to hrhsimonn's post “On the first question, it...”
On the first question, it says my answer is wrong and I got 18 as my answer.
Button navigates to signup pageComment on hrhsimonn's post “On the first question, it...”
(58 votes)
Answer
- Ryenn Smith
  Posted 3 years ago. Direct link to Ryenn Smith's post “At first i got that too, ...”
  At first i got that too, but then i realized there was a -6 at the end of the problem. So the actual answer was 12. :)
  Comment on Ryenn Smith's post “At first i got that too, ...”
  (61 votes)
Xinyi Ni
Posted 3 years ago. Direct link to Xinyi Ni's post “i dont get the 2nd q how ...”
i dont get the 2nd q how do we solve it when its an fraction
Button navigates to signup pageComment on Xinyi Ni's post “i dont get the 2nd q how ...”
(16 votes)
Answer
- loumast17
  Posted 3 years ago. Direct link to loumast17's post “a fraction is division. ...”
  a fraction is division. so 10 divided by 5 can be written as a fraction 10/5, and x/y means x divided by y. does that help? you would do it along with multiplication in the order of operations.
  Comment on loumast17's post “a fraction is division. ...”
  (21 votes)
Ayesha Griffith
Posted 7 years ago. Direct link to Ayesha Griffith's post “how do you expand and sim...”
how do you expand and simplify: 2(x- 1)(x+1)+(2x-1)(2x-1)
Button navigates to signup pageButton navigates to signup page
(8 votes)
Answer
- Math with Courtney
  Posted 7 years ago. Direct link to Math with Courtney's post “First distribute 3x over ...”
  First distribute 3x over (2x+5) and then distribute -2x over (x-6):
  3x(2x+5) - 2x(x-6)
  = 6x^2 + 15x - 2x^2 + 12x [Note: -2x * -6 = +12x, not -12x]
  = 6x^2 - 2x^2 + 15x + 12x [Rewrite with like terms in order.]
  = 4x^2 + 27x
  Button navigates to signup page
  (15 votes)
Bookworm
Posted 6 years ago. Direct link to Bookworm's post “how can i find the answer...”
how can i find the answer in the equation 5x - x/y when x=4 and y =2
Button navigates to signup pageComment on Bookworm's post “how can i find the answer...”
(6 votes)
Answer
- Kim Seidel
  Posted 6 years ago. Direct link to Kim Seidel's post “1) Substitute each value...”
  1) Substitute each value into the expression for their respective variable
  5(4) - 4/2
  2) Follow PEMDAS
  -- Multiply: 20 - 4/2
  -- Divide: 20 - 2
  -- Subtract: 18
  Hope this helps.
  Comment on Kim Seidel's post “1) Substitute each value...”
  (11 votes)
Billy Wells
Posted 3 years ago. Direct link to Billy Wells's post “After coming back from th...”
After coming back from the Holiday BELIEVE ME! I had to go through these problems more than (2)- (3) times. Knowing how much I love math this, probably was one of the toughest days ever. This is how I solved the First and second problems:

10+2p-3k ( p=4, r=5)
10 +2*4-3*5
10+8-15
18-15=3

6a+4b-6 ( a=1, b=3)
6*1+4*3-6
6+12-6
18-6=12
Button navigates to signup pageComment on Billy Wells's post “After coming back from th...”
(10 votes)
Answer
- nahnahihalima09
  Posted 16 days ago. Direct link to nahnahihalima09's post “That is correct! Great jo...”
  That is correct! Great job!
  Button navigates to signup page
  (1 vote)
Viki Morgan
Posted 7 years ago. Direct link to Viki Morgan's post “How come when evaluating ...”
How come when evaluating expressions with two variables (the previous section) that the minus was completed prior to the plus. The questions was xy - y + 3x where x = 3 and y =2. BOMDAS 3 x 2 - 2 + 3 x 3 =
6 - 2 + 9
6 - 11
Button navigates to signup pageComment on Viki Morgan's post “How come when evaluating ...”
(4 votes)
Answer
- dashpointdash
  Posted 7 years ago. Direct link to dashpointdash's post “xy-y+3x , if x=3 and y=2 ...”
  xy-y+3x , if x=3 and y=2 results to 6 - 2 + 9 = 13.
  
  Either a parenthesis in the exercise got lost or the solution is wrong,
  but for the given expression the above result is the correct solution.
  Comment on dashpointdash's post “xy-y+3x , if x=3 and y=2 ...”
  (12 votes)
delgadoloveo
Posted 3 years ago. Direct link to delgadoloveo's post “I still don’t get 5 * y -...”
I still don’t get 5 * y - x/y when x= 4 and y=2
Button navigates to signup pageComment on delgadoloveo's post “I still don’t get 5 * y -...”
(7 votes)
Answer
- justdoingit
  Posted 3 months ago. Direct link to justdoingit's post “First things first the qu...”
  First things first the question above is 5x - x/y
  You copied it wrong
  Even if you want the answer, here you go
  Your question is- 5 * y - x/y
  Let's substitute-5 * 4 - 4/2
  Which gives us 5 * 4 - 2
  20 - 2 = 8
  Hope that helped
  Button navigates to signup page
  (4 votes)
marmellini888
Posted 3 years ago. Direct link to marmellini888's post “Please help me understand...”
Please help me understand answer from video demonstration
xy-y+3x, where x = 3 and y = 2
3(2)-2+3(3)
6-2+9
The answer is given as 13
Why isn't it 6-(2+9)= -5
Button navigates to signup pageButton navigates to signup page
(4 votes)
Answer
- David Severin
  Posted 3 years ago. Direct link to David Severin's post “Because that is not a way...”
  Because that is not a way to group. Both 6 and 9 are positive and 2 is negative, so you could associate (6+9)-2, but not as you show which makes the 0 negative on distribution
  Comment on David Severin's post “Because that is not a way...”
  (5 votes)
calvinb0715
Posted 3 years ago. Direct link to calvinb0715's post “how would i do 5x-x/y whe...”
how would i do 5x-x/y when x is 4 and y is 2
Button navigates to signup pageComment on calvinb0715's post “how would i do 5x-x/y whe...”
(4 votes)
Answer
- 管墨涵
  Posted 3 years ago. Direct link to 管墨涵's post “First, we need to plug th...”
  First, we need to plug the numbers into the expression.
  So, 5x-x/y becomes 5 x 4 - 4/2.
  Next, we need to follow PEMDAS, so we need to do the multiplication and division first.
  Then, this expression becomes 20 - 2.
  And the result is 18.
  I hope it helps.
  Comment on 管墨涵's post “First, we need to plug th...”
  (8 votes)
nhannwe.oo
Posted 2 years ago. Direct link to nhannwe.oo's post “What is the 6a+4b-6 whan ...”
What is the 6a+4b-6 whan a = 1 and b=3 I'm Don't know how to do
Button navigates to signup pageButton navigates to signup page
(4 votes)
Answer
- .꧁𝓝𝓸𝓿𝓪꧂.
  Posted 2 years ago. Direct link to .꧁𝓝𝓸𝓿𝓪꧂.'s post “Just plug in the values o...”
  Just plug in the values of a and b. 6a + 4b - 6 becomes:
  
  6(1) + 4(3) - 6 or (6 * 1) + (4 * 3) - 6,
  
  You'll get 6 + 12 - 6. Use PEMDAS to find that addition comes first. So you can rewrite it as (6 + 12) - 6 which is 18 - 6.
  
  Your final answer should be 12.
  Comment on .꧁𝓝𝓸𝓿𝓪꧂.'s post “Just plug in the values o...”
  (7 votes)