If you include the following brackets, you are correct.
I will cut-and-paste your answer , and put in the necessary brackets
(x-21)/(x^2-9) - x/(3-x)
so I did (x-21)/((x-3)(x+3)) - x/-(x-3)
= (x-21+x(x+3) )/((x-3)(x+3))
= (x-21+x^2+3x)/((x-3)(x+3))
4x-21+x^2/((x-3)(x+3))
= (x^2+4x-21)/((x-3)(x+3))
= ( x(x+7)-3(x+7) )/((x-3)(x+3))
= (x+7)(x-3)/((x-3)(x+3)) the x-3 cancel out
= (x+7)/(x+3) , x ≠ 3
Your answer is correct, have you learned about restrictions?
x-21/(x^2-9) - x/(3-x)
so I did x-21/((x-3)(x+3)) - x/-(x-3)
x-21+x(x+3)/((x-3)(x+3))
x-21+x^2+3x/((x-3)(x+3))
4x-21+x^2/((x-3)(x+3))
x^2+4x-21/((x-3)(x+3))
x(x+7)-3(x+7)/((x-3)(x+3))
(x+7)(x-3)/((x-3)(x+3)) the x-3 cancel out
so the answer is x+7/x+3 is this correct? Thank you
3 answers
You answer is correct.
sorry, no we did not learn restrictions.
Thank you for checking my work.
Thank you for checking my work.