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## Get ready for Algebra 1

### Course: Get ready for Algebra 1>Unit 4

Lesson 4: Linear models

# Modeling with linear equations: snow

Sal uses a linear equation to model the amount of snow on the ground. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• I'm sure at least a few of us who are here have been taught to (when there's a need for it) to use the equation y = mx + c where m is the slope coefficient and c is at which point of y, x = 0 is crossed. I'm somewhat confused at the order of terms and constants at - how can one write the c and -mx terms the opposite way? Does it even matter?
• To build on what Ansh said, and to answer the original question: yes, they are the same thing, but arranged differently. What Sal wrote was essentially: y=b+(-m)x. That can be re-arranged (through the commutative property) in the format that you're used to: y=(-m)x+b. So, y=12-2x is also y=-2x+12
• At , is the 2x multiplication?
• The x is not a multiplication sign if that's what you mean, but the expression 2x is using "x" as a variable to represent the number of days since Monday and multiplying it by 2 since 2 inches of snows melts for every day that passes.
• How do I be able to find out which angle forms a linear angle or ajacent angle using some of these formulas that Sal showed in the video?
• the problem in the video was to graph or discover an equation, not be able to us e it for solving the adjacent line. It was a linear equation you know.
• so are we supposed to use y=mx+b?
• Yes! I'm pretty sure that's correct. y is y, m is -2, x is x, and b is 12. y=mx=+b = y=-2x+12
• how many inches of snow was on the ground on Thursday.
• There where 6 inches couldn't you figure it out?
• I need help with point-slope form of a line
• I can help you but what do you need to help with exactly.
• Slope is m=deltaY÷deltaX which in case of the video is -2. I mean that's rationally constant and so can we really technically call it to be constant those simple Y÷X is not coming constant. Thank you!
• y/x is only constant when it is a direct proportion problem (that means the line goes through the origin). As soon as you have a y intercept other than 0, then it is not constant.
• If i make an arithmetic sequence for the above problem then for an nth term an=14-2n but in the video y=12-2x? I mean, n is just the number of term we are finding in the sequence and x is exactly the same thing a number on x axis for which we are finding y. But why do we have 14 in one and 12 in the other? Thanks!
• For an arithmetic sequence, it should be related to n-1, not n. Formula is generally expressed as an=a1+(n-1)d. a1=10 and d=2. So the formula should be an=10-2(n-1).