Математика- 120:3=40мин-1/3 2- 60:4=15
<span>1) 8у-3(2у-3)=7у-2(5у+8);</span>
8y-6y+9=7y-10y-16
8y-6y -7y+10y=-16-9
5y=-25
y=-25/5
y=-5
<span>2)5(2у-9)+6у=4(3у-2)-21;
10y-45+6y=12y-8-21
10y+6y-12y=45-29
4y=16
y=16/4
y=4</span>
<span><span>3)5у+7(3-у)=3(5-2у)-6;</span></span>
<span><span>5y+21-7y=15-6y-6
5y-7y+6y=9-21
4y=-12
y=-12/4</span></span>
<span><span>y=-3
</span></span>
<span><span><span>4)7у-4(3у+5)=2-3(4у-9)</span></span></span>
<span><span><span>7y-12y-20=2-12y+27
7y-12y+12y=2+27+20
7y=49
y=49/7</span></span></span>
<span><span><span>y=7 </span></span></span>
<span> </span>
4-x²-2xy-y²=<span>4-(x²+2xy+y²)=2</span>²-(х+у)²=(2-(х+у))(2+(х+у))=(2-х-у)(2+х+у)
1) 3х-15=х+3
3х-х=3+15
2х=18
х=9
2) 7-3х=х+11
-3х-х=11-7
-4х=4
х=-1
3) 2(х+3)=х+13
2х+6=х+13
2х-х=13-6
х=7
4) 4(5-х)=3х-1
20-4х=3х-1
-4х-3х=-1-20
-7х=-21
х=3
5) 3(х-2)=х+4
3х-6=х+4
3х-х=4+6
2х=10
х=5
6) 5(х-1)=4х+3
5х-5=4х+3
5х-4х=3+5
х=8