Answer: 2x - 1
Explanation:
Given;
F(x) = 2x + 5........... *
we are to find F(x + 3 )
The first thing we will do is to equate x and x + 3 but it is clear that x in not equal to x + 3 , so we will write it as :
x = y + 3 and then make y the subject of the formula:
x = y + 3, that is
y = x - 3
This means that y(x) = f(x-3)
substitute x - 3 for x in the original expression given , that is
F(x+3) = 2 ( x - 3 ) + 5
F( x +3 ) = 2x - 6 + 5
F(x + 3) = 2x - 1