To silpify the expression we proceed as follows: (x+7)/(x^2+4x-21) Factorizing the given the denominator: x^2+4x-21 x^2-3x+7x-21 =x(x-3)+7(x-3) =(x-3)(x+7) thus plugging back in our expression we have: (x+7)/[(x-3)(x+7)] simplifying this we obtain: 1/(x+3)
