Решите через дескриминат 1) (х-2)(12-х)=9 2) (х+1)^2=3(х+7)

Question

Решите через дескриминат
1) (х-2)(12-х)=9
2) (х+1)^2=3(х+7)

Answer 1

(х-2)(12-х)=9

12x-x^2-24+2x=9

14x-x^2-24-9=0

x^2-14x+33=0

D=(-14)^2-4*1*33==196-132=64=8^2

x1=(14+8)/2=11

x2=(14-8)/2=3

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(х+1)^2=3(х+7)

x^2+2x+1=3x+21

x^2+2x+1-3x-21=0

x^2-x-20=0

D=(-1)^2-4*1*(-20)=1+80=81=9^2

x1=(1+9)/2=5

x2=(1-9)/2=-4