Question

(x+4)*(x-7)>3*(x-7)

 

Помогите, нужно решение! Срочно!

Answer 1

x^2-28-3x>3x-21

x^2-6x-7>0

x1=-1

x2=7

x<-1 U x>7

Answer 2

X^2 - 7X + 4X - 28 > 3X - 21

X^2 - 3X - 28 > 3X - 21

X^2 - 3X - 3X - 28 + 21 > 0

X^2 - 6X - 7 > 0

D = 36 - 4*1*(-7) = 36 + 28 = 64

V D = 8

X1 = 6 + 8 2 = 7

X2 = 6 - 8 2 = - 1

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(X - 7) *(X +1 ) > 0

X - 7 > 0 ---> X > 7 

X + 1 > 0 ----> X > - 1

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