6х-120=0 -х+8=29
6х=120 -х=29-8
х=120:6 -х= -21
х=20
6*20-120=0 -(-21)+8=29
(a-3)²-a(5a-6)=a²-6a+9-5a²+6a=9-4a²=(3-2a)(3-2a)<span>вот и все</span>
- 8( 11 – 2а) + 40 = 3(5а – 4)-88 + 16а + 40 = 15а - 2016а -15а = -88 + 40 + 20а= -28
7y^2-4xy-4x^2+4xy-y^2=6y^2-4x^2=6*10-4*28=60-112=-52