Question

Решите
1)a(а- 3) =2a-6
2)х(х+4)-(х+4)=0​

Answer 1

a(а- 3) =2a-6

2а-3а=2а-6

2а-3а-2а=-6

-3а=6

а=-2

х(х+4)-(х+4)=0​

2х+4х+(-х)-4=0

6х+(-х)-4=0

6х+(-х)=0+4

5х=4

х=1,25

Answer 2

$a(a-3)=2a-6\\a^2-3a=2a-6\\a^2-3a-2a-6=0\\a^2-5a-6=0\\D=b^2-4ac=(-5)^2-4*1*(-6)=25+24=49\\x_{1}=\frac{-b-\sqrt{D} }{2a} =\frac{5-7}{2}=-\frac{2}{2}=-1\\x_{2}=\frac{-b+\sqrt{D} }{2a}=\frac{5+7}{2}=\frac{12}{2}=6$

$x(x+4)-(x+4)=0\\x^2+4x-x-4=0\\x^2+3x-4=0\\D=b^2-4ac=(3)^2-4*1*(-4)=9+16=25\\x_{1}=\frac{-b-\sqrt{D} }{2a} =\frac{-3-5}{2}=-\frac{8}{2}=-4\\x_{2}=\frac{-b+\sqrt{D} }{2a}=\frac{-3+5}{2}=\frac{2}{2}=1$