FUNCTIONS 4

Find a linear function f(x) with gradient -20 which is such that f(5)=12.

        Solution.

m=-20, points = [5,12] and [x, f(x)]

m = y₂-y₁/x₂-x₁

-20 = f(x) – 12/x-5

f(x)-12=-20(x-5) [after cross multiply]

f(x)-12=-20x+100

f(x)=-10x+100+12

f(x)=-10x+112

Hence A  linear function is f(x) = -10x+112.

TRY THIS……….

Give out a linear function f(x) with gradient 11 and f(5)=16.