FUNCTIONS E1

 

Find a linear function f(x) with gradient -6 which is such that f(8)=12.

 

       Solution.

 

m=-6, points = [8,12] and [x, f(x)]

 

m = y₂-y₁/x₂-x₁

 

-6 = [f(x) – 12]/x-8

 

 

f(x)-12=-6(x-8) [after cross multiply]

f(x)-12=-6x+48

f(x)=-6x+48+12

f(x)=-6x+60

 

A  linear function is f(x) = -6x+ 60.

 

TRY THIS……….

 

Give out a linear function f(x) with gradient -5 and f(6)=19