Question

simplify the rational expression x^2 - 81 / x^2 + 18x + 81

a) x - 9 / x + 9
b) x + 9 / x + 9
c) x + 9 / x - 9
d) x - 9 / x - 9

a

Answer 1

yes, it is a because you factor...

x^2-81= x-9(x+9)
x^2+18x-81= (x+9)(x+9)
check:
9x+9x= 18x
x*x= x^2
-9*9= -81

((x-9)(x+9))/((x+9)(x+9))-> cross out x+9

ANS:(x-9)/(x+9)

Answer 2

thanks Nancy