Question

Решите уравнение (x+9)^2-(x-5)(x+5)=79

Answer 1

$(x + 9) {}^{2} - (x - 5)(x + 5) = 79 \ x {}^{2} + 18 + 81 - (x {}^{2} - 25) = 79 \ x {}^{2} + 18x + 81 - x {}^{2} + 25 = 79 \ 18x + 106 = 79 \ 18x = 79 - 106 \ 18 = - 27 div 18 \ x = - 1.5$