5) (a+b)³-(a-b)³=((a+b)-(a-b))*((a+b)²+(a+b)(a-b)+(a-b)²)=(a+b-a+b)(a²+2ab+b²+a²-b²+a²-2ab+b²)
Сокращаем
2b(3a²+b²)= 6a²b+2b³
6)((a+b)²-(a-b)²)(( a+b)²+(a-b)²)=(a²+2ab+b²-(a²-2ab+b²))( a²+2ab+b²+a²-2ab+b²)
Сокращаем
4ab*2(a²+b²)=8a³b+8ab³
Ответ:
Объяснение:
(sin15°)^4+(cos15°)^4=(sin²15°+cos²15°)²-2sin²15°×cos²15°=1-2sin²15°×cos²15°=1-2×sin15°×cos15°×sin15°×cos15=1-2×sin15°×cos15°×2×sin15°×cos15/2=1-(sin30°)²/2=1-(0,5)²/2=1-0,125=0,875
<span><span>y</span>+(5y+2)²=25(2+y²)
y+25y²+20y+4=50+25y²
25y²+21y-25y²=50-4
21y=46
y=46/21
y=2 4/21
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1) х+2=9
х=9-2
х=7
2) -х-2=9
-х=9+2
-х=11 |:(-1)
х=-11