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Adding integers: find the missing value

Use number lines to find missing addends in addition equations with integers. When we add a positive value, we move to the right on the number line. When we add a negative value, we move to the left. Created by Sal Khan.

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• so what if the problem looks like this (-29)-29 how would I find out the sum also my teacher said that when it looks something like 18-41 u make the 41 into a negative and change the whole problem into a addition problem but I don't under stand it also for reference im in 9th grad algebra 1 so just to make sure im getting the right answer ok bye
• So say you have a number line, -29 is 29 to the left of 0, then you move it another 29 spaces to the left and you have ur answer. Another way to think of it so if i for example have -2-2 i would just do 2+2=4 then slap a negative on and voila! The answer is -4
• or you can do two step equation

let x be the missing number

4 + x = -6

4 + x = -6
4 - = -4

-4 + -6 = -10

x = -10

4 + -10 = -6
• what is the hardest math problem
• Question 6 of the 1988 math Olympaid.
It is famous.

Let a and b be positive integers such that ab + 1 divides a2 + b2. Show that a2 + b2 / ab + 1 is the square of an integer.
• watch me nay nay
• Also I have more trouble with the equasions like -2-(-2)
• - & + = -
+ & - = -
- & - = +
+ & + = +
Anybody tell me how the last 2 works? Thats like 2 bad luck= a good luck. And how does 2+ dont cancel out?