Trig question

Question

If f(x)=x^2

 

 Find:     f(x+h)-f(x-h)

               -------------------?(that's a fraction btw)

                      2h

 

Please help!! Iv'e tried to solve this for forever:(

 

Answer 1

when you have a function such as

f(x) = x²   it means that whatever you

put inside the parenthesis for x you

square it to get the output.

 

If f(x) = x² then:

f(x+h) = (x+h)² = x² + 2xh + h²

f(x-h) = (x-h)² = x² - 2xh + h²

 

f(x+h)-f(x-h)

---------------  = 

       2h

 

x²+2xh+h² - (x²-2xh+h²)

---------------------------    =

             2h

 

x² + 2xh + h² - x² + 2xh - h²

--------------------------------  =

            2h

 

   4xh

  -----  =   2x

    2h

Answer 2

(x+h)² - (x-h)² = x² +2xh + h² - (x² -2xh +h²) = 4xh then divide by 2h and get 2x