The expression [tex]$\frac{f(x+h)-f(x)}{h}$[/tex] for [tex]$h \neq 0$[/tex] is called the difference quotient.

Find and simplify the difference quotient for the following function:
[tex]
f(x)=-3x^2+5x+5
[/tex]

Simplify your answer.



Answer :

To find and simplify the difference quotient for the function [tex]\( f(x) = -3x^2 + 5x + 5 \)[/tex], follow these steps:

1. Write the expression for the difference quotient:

[tex]\[ \frac{f(x+h) - f(x)}{h} \][/tex]

2. Substitute [tex]\( f(x) = -3x^2 + 5x + 5 \)[/tex] into the quotient:

[tex]\[ f(x) = -3x^2 + 5x + 5 \][/tex]

3. Find [tex]\( f(x+h) \)[/tex]:

Substitute [tex]\( x+h \)[/tex] into the function [tex]\( f \)[/tex]:

[tex]\[ f(x+h) = -3(x+h)^2 + 5(x+h) + 5 \][/tex]

Expand [tex]\( (x+h)^2 \)[/tex]:

[tex]\[ (x+h)^2 = x^2 + 2xh + h^2 \][/tex]

Then,

[tex]\[ f(x+h) = -3(x^2 + 2xh + h^2) + 5(x+h) + 5 \][/tex]

Simplify:

[tex]\[ f(x+h) = -3x^2 - 6xh - 3h^2 + 5x + 5h + 5 \][/tex]

4. Compute [tex]\( f(x+h) - f(x) \)[/tex]:

[tex]\[ f(x+h) - f(x) = (-3x^2 - 6xh - 3h^2 + 5x + 5h + 5) - (-3x^2 + 5x + 5) \][/tex]

Distribute the negative sign and combine like terms:

[tex]\[ f(x+h) - f(x) = -3x^2 - 6xh - 3h^2 + 5x + 5h + 5 + 3x^2 - 5x - 5 \][/tex]

Simplify:

[tex]\[ f(x+h) - f(x) = -6xh - 3h^2 + 5h \][/tex]

5. Divide by [tex]\( h \)[/tex]:

[tex]\[ \frac{f(x+h) - f(x)}{h} = \frac{-6xh - 3h^2 + 5h}{h} \][/tex]

6. Simplify the resulting expression:

[tex]\[ \frac{f(x+h) - f(x)}{h} = \frac{h(-6x - 3h + 5)}{h} \][/tex]

Cancel [tex]\( h \)[/tex] in the numerator and denominator (since [tex]\( h \neq 0 \)[/tex]):

[tex]\[ \frac{f(x+h) - f(x)}{h} = -6x - 3h + 5 \][/tex]

Therefore, the simplified difference quotient for the function [tex]\( f(x) = -3x^2 + 5x + 5 \)[/tex] is:

[tex]\[ -6x - 3h + 5 \][/tex]