<span>(16x-27y-20)²=0
(5x+18y-41,5)²</span>=0
<span>16x-27y-20=0
5x+18y-41,5=0</span>
<span>16x-27y=20 *2 32x-54y=40
5x+18y=41,5</span> *3 15x+54y=124,5
47x=164,5 x=3,5 y=4/3
(1-a)(2a+b)-(2+a)(1-b)=2a+b-2a²-ab-2+2b-a+ab=-2a²+a+3b-2
(2a-b)(a+b)-(a+2b)(a-b)=2a²+2ab-ab-b²-a²+ab-2ab+2b²=a²+b²
(3-m)(8+n)+(m-4)(n+6)=24+3n-8m-mn+mn+6m-4n-24=-n-2m
<span>(9m-2n)(2m+n)-(6m+n)(3m-2n)=18m</span>²+9nm-4nm-2n²-18m²+12nm-3nm+2n²=14nm