Answer:
A
[tex]f(x + h) = 21x -x^2 -2xh+ 21h+h^2[/tex]
B
[tex]f(x-h)-f(x) = 21h+h^2 -2xh[/tex]
C
[tex]\frac{f(x-h)-f(x)}{h} = 21+h -2x[/tex]
Step-by-step explanation:
From the question we are told that
The equation given is
[tex]f(x) = x (21 - x )[/tex]
Considering A
[tex]f(x + h) = (x + h) (21 - (x + h))[/tex]
[tex]f(x + h) = (x + h) (21 - x - h)[/tex]
[tex]f(x + h) = 21x -x^2 -2xh+ 21h+h^2[/tex]
Considering B
[tex]f(x + h)-f(x) = 21x -x^2 -2xh+ 21h+h^2 -[ x(21 -x)][/tex]
[tex]f(x + h)-f(x) = 21x -x^2 -2xh+ 21h+h^2 -21x + x^2[/tex]
[tex]f(x-h)-f(x) = 21h+h^2 -2xh[/tex]
Considering C
[tex]\frac{f(x-h)-f(x)}{h} = \frac{21h+h^2 -2xh}{h}[/tex]
[tex]\frac{f(x-h)-f(x)}{h} = \frac{h(21+h -2x)}{h}[/tex]
[tex]\frac{f(x-h)-f(x)}{h} = 21+h -2x[/tex]
