12 баллов.
Решите уравнения:
а) 9x^2-7x-2=0
б) х^2+18х-63=0.

a) 9x² - 7x - 2 = 0D = b² - 4ac = 49 - 4×9×(-2)= 49 + 72 = 121 = 11²x1 = ( 7 + 11) / 18 = 1x2 = (  7 - 11) / 18 = - 4/18 = - 2/9б) x² + 18x - 63 = 0D = b² - 4ac = 324 - 4×(-63) = 576 = 24²x1 = ( - 18 + 24) / 2 = 3x2 = ( - 18 - 24) / 2 = - 21