а) М+(3ху-2у²)=х²+ху-у²
<span>(х</span>²<span>-2ху+у</span>²<span>)+(3ху-2у</span>²<span>)=х</span>²<span>+ху-у</span>²<span> </span>
<span>
б) М-(4ху+3у</span>²<span>)= х</span>²<span>+ху-у</span><span>²</span>
<span>(х</span>²<span>+5ху+2у</span>²<span>)-(4ху+3у</span>²<span>)=
х</span>²<span>+ху-у</span><span>²</span>
63/180=x/100
180x=6300
x=630:18
x=35
Ответ: 35%
(а+5)^2= а^2+10a+25
(3x-x)^2=9x^2-6x-x^2
(2b-1)(2b+1)=4b^2-1
(4a+3b)(4a-3b)=16a^2-9b^2