FUNCTIONS B2

 

Find a linear function f(x) with gradient -6 which is such that f(5)=14.

 

Solution.

 

m=-6, points = [5,14] and [x, f(x)]

 

m = y₂-y₁/x₂-x₁

 

-6 = [f(x) – 14]/x-5

 

f(x)-14=-6(x-5)  [after cross multiplying]

 

f(x)-14=-6x+30

 

f(x)=-6x+30+14

 

f(x)=-6x+44

 

Hence a linear function is f(x) = -6x + 44.

 

TRY THIS……….

 

Give out a linear function f(x) with gradient -7 and f(2)=12