<span> 2x+y=3 4x-2y=14умножим первое на 2
</span><span> 4x+2y=6 4x-2y=14 вычтем из первого второе
4у=-8
у=-8/4
у=-2
подставим в первое 2х-2=3
2х =5
х=2,5
ответ(2,5;-2)
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15^(2-log(15)9)=15²:15^log(15)9=225:9=25
2log(1/5)5+log(1/5)3+0,5log(1/5)225=log(1/5)25+log(1/5)3+log(1/5)15=
=log(1/5)(25*3*15)=log(1/5)(125*9)=log(1/5)125+log(1/5)9=-3+2log(1/5)3
49^(log(7)2+log(√7)2-1/2*log(49)64)=
=49^(log(7)2)* 49^(log(√7)2):49^(1/2*log(49)64))=
7^(log(7)4 *(√7)^log(√7)16 : 49^log(49)8=4*16:8=8
<span>2x(x−20)</span>²<span>−x</span>²<span>(x−20)=0
x-(x-20)*(2x-40-x)=0
x*(x-20)*(x-40)=0
x=0 x</span>₁=0<span>
x-20=0 x</span>₂=20<span>
x-40=0 x</span>₃=40<span>
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№1
2х² - 20ху + 50у² = 2(х² - 10ху + 25у²) = 2(x - 5y)²
№2
1 )х²у - 36у³ = y(x² - 36y²) = y(x - 6y)(x + 6y)
2) а³ + 8с³ = (a +2c)(a² - 2ac + 4c²)
3) -5m² + 10mn - 5n² = -5 (m² - 2mn + n²) = -5 (m - n)²
№3
1) а^4 - 81 = (a² - 9)(a² + 9) = (a - 3)(a + 3)(a² + 9)
2) 4ас - 28с + 8а - 56 = 4c(a - 7) + 8(a - 7) = (4c + 8)(a - 7) = 4(c + 2)(a - 7)