Find equation of linear function.

Question

Find an equation of a linear function given h(l)=6 and h(4)=-3.

Answer 1

h = mx + b,

 

where x is a variable, and m and b are constants.  Use the given information to find m and b:

 

 6 = m(1) + b

-3 = m(4) + b

 

Subtract top equation from bottom equation and get

 

-9 = 3m

 

m = -3

 

Substitute m into either equation to get b.  Using the top equation,

 

6 = (-3)*1 + b = -3 + b

 

b = 9

 

The equation is 

 

h = -3x + 9

 

Go ahead and test the solution.