Question

Найдите корни уравнения:
А) х2-5х-24=0
б) х2-13х+42=0

Answer 1

$\displaystyle\bf\\1)\\\\x^{2} -5x-24=0\\\\D=(-5)^{2} -4\cdot 1\cdot(-24)=25+96=121=11^{2} \\\\\\x_{1} =\frac{5-11}{2} =\frac{-6}{2}=-3\\\\\\x_{2} =\frac{5+11}{2} =\frac{16}{2} =8\\\\\\Otvet \ : \ -3 \ , \ 8\\\\2)\\\\x^{2} -13x+42=0\\\\D=(-13)^{2} -4\cdot 1\cdot 42=169-168=1\\\\\\x_{1} =\frac{13-1}{2} =\frac{12}{2}=6\\\\\\x_{2} =\frac{13+1}{2} =\frac{14}{2} =7\\\\\\Otvet \ : \ 6 \ , \ 7$