1) 25y-y^3=y(25-y^2)=y(5-y)(5+y)
2) 20x+5(x-2)^2=20x+5(x^2-4x+4)=20x+5x^2-20x+20=5x^2+20=5(x^2+4)
3) (x-3)^2-16=0
(x-3)^2=16
x-3 = 4 x-3=-4
x= 7 x=-1
<span>Раскрываем скобки и приводим подобные слагаемые:
3m-(2n-3(n-m+1)+n) = 3m-(2n-3n+3m-3+n)=3m-(3m-3)=3m-3m+3=3 Доказано!
</span>
A²-b²+2ab-1=(a-b)²-1²=(a-b+1)(a-b-1)
3.1у-3-4(6.2у+0.2)=3.1у-3-24.8у-0.8=3.1у-24.8у-0.8= -21,7у-0,8
(x-4)^2-x^2=12
x^2-8x+4-x^2=12
-8x+4=12
-8x=8
x=-1
25y^2-1-(5y-2)^2=0
25y^2-1-(25y^2-20y+4=0
25y^2-1-25y^2+20y-4=0
-1+20y-4=0
-5+20y=0
20y=5
y=4