Question

Через D=b^2-4ac 8 класс

Answer 1

Ответ и объяснение:

$1)\ x^2+2x-24=0\\D=2^2-4*1*(-24)=4+96=100\\x_{1/2}=\dfrac{-2б10}{2}\\\\x_1=\dfrac{-2-10}{2} =\dfrac{-12}{2} = -6\\\\x_2=\dfrac{-2+10}{2} = \dfrac{8}{2} = 4$

$2)\ x^2-9x+20=0\\D=(-9)^2-4*1*20=81-80=1\\x_{1/2} =\dfrac{9б1}{2}\\\\x_1=\dfrac{9-1}{2} = \dfrac{8}{2} = 4\\\\x_2=\dfrac{9+1}{2} =\dfrac{10}{2} = 5$

$3)\ 10n^2-9n+2=0\\D = (-9)^2-4*10*2=81-80=1\\x_{1/2} =\dfrac{9б1}{20}\\\\x_1=\dfrac{9-1}{20} =\dfrac{8}{20} = \dfrac{2}{5} =0,4\\\\x_2=\dfrac{9+1}{20} =\dfrac{10}{20} =\dfrac{1}{2} = 0,5$