1) <span>х+Y=7
2Х+Y=8
у=7-х
2х+7-х=8
х=1
у=6
2)</span><span>3Х-2Y=5
Х+2Y=15
х=15-2у
45-6у-2у=5
-8у=-40
у=5
х=15-10=5
3)</span><span>Х+Y=5
3Х+Y=7
у=5-х
3х+5-х=7
2х=2
х=1
у=4
4)</span><span>3Х+2Y=7
Х-2Y=-3
х=-3+2у
-9+6у+2у=7
8у=16
у=2
х=1</span>
=7a^2-2a+7
=-4ab
=-x^2-10x-1
=54m^2-36x
=68x^2-12x
=3m^2-7m+17
=4xy
=-32a^2+20ab+7b^2
1) a+a+d+a+2d=24;
3a+3d=24;
a+d=8;
a=8-d.
2) a²+(a+d)²+(a+2d)²=210;
a²+d²+16d-82=0;
(8-d)²+d²+16d-82=0;
d²=9;
d=3 или d=-3;
a1=8-3=5, a2=8, a3=11;
или
a1=8+3=11, a2=8, a3=5.
Ответ: 5;8;11 или 11;8;5.
=(m+n)^2+mn-m^2=(m+n+m)(m+n-m)+mn=(2m+n)n+mn=2mn+n^2+mn=3mn+n^2=n(3m+n)