2x + x = 120
3x = 120
x = 40
длина — 40 + 40 = 80
ширина — 40
S = 40 * 80 = 3200
X⁵-x³+x²-1=x³*(x²-1)+(x²-1)=(x²-1)*(x³+1)=(x+1)*(x-1)*(x+1)*(x²-x+1)=(x+1)²*(x-1)*(x²-x+1)
<span>3(x-7)+4=7x-1
3x-21+4=7x-1
3x-7x=21-4-1
-4x=16
x=-4</span>
X²-3x-10=0
x1+x2=3 U x1*x2=-10⇒x1=-2 U x2=5
(x+2)²(x-5)²+(x-5)²(x+5)²=0
(x-5)²[(x+2)²-(x+5)²]=0
(x-5)²(x+2-x-5)(x+2+x+5)=0
-3(x-5)²(2x+7)=0
x-5=0
x=5
2x+7=0
x=-3,5
13,8х-6-3,5х+0,7х=0,5х-7
13,8х-3,5х+0,7х-0,5х=-7+6
11х=-1
Х=-1/11