If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Lesson 13: Linear and nonlinear functions

# Linear & nonlinear functions: word problem

Learn to determine if the relationship described in a word problem is a function. Created by Sal Khan.

## Want to join the conversation?

• y=mx+b is a slope form. We use this to tell if it is a function or not. If it follows the formula y=mx+b then you know that it is proportional.
• what would the linear equation be, if on a table the x value was 0, and the y value was 49, and the y value kept decreasing by -35 and the x value kept rising by 1.?
• I think that it would be: y=14x, and the y-intercept would be 0. The next two values in the table would be 14 and 1 because 49-35=14 and 0+1=1. Since 14 divided by 1 is still 14, the slope would be 14.
• is b the slope or initial value
• B is the y-intercept. that means where the line meets with the y-axis. you could also look at it like this. y=mx+b, if x equals 0 then m*0 is 0 then y would equal B. So B is the y-intercept(M is the slope).
• Say, (x) increases by 3 each time but what if (y) increased gradually. for example (x) goes, (1,3,6,9,12) and (y) went (4,5,7,10,14) would that be a linear or non-linear?
• It is definitely not linear, remember slope is (y2-y1)/(x2-x1) and this has to stay the same between any two points. The first two give (5-4)/(3-1)=1/2. The second and third give (7-5)/(6-3)=2/3 which are not the same.
• What's a non-linear example then?
(1 vote)
• A eagle is diving into the water to catch a fish. He sees the fish when he is 20 feet above the water, he then dives to two feet below the surface and catches the fish, and 10 seconds after he started to dive he rose back to 20 feet. Find a quadratic equation which approximates the path the eagle travelled.