✨ ベストアンサー ✨
(2)X²(X-Y)-X(X-Y)²
=X²(X-Y)-X(X-Y)(X-Y)
◎(X-Y)でくくる
=(X-Y)[X²-X(X-Y)]
=(X-Y)[X²-X²+XY]
=(X-Y)XY
(4)a³(X+3Y)-aX²(X+3Y)
◎a(X+3Y)でくくる
=a(X+3Y)[a²-X²]
◎公式 X²-Y²=(X+Y)(X-Y)
=a(X+3Y)(a+X)(a-X)
✨ ベストアンサー ✨
(2)X²(X-Y)-X(X-Y)²
=X²(X-Y)-X(X-Y)(X-Y)
◎(X-Y)でくくる
=(X-Y)[X²-X(X-Y)]
=(X-Y)[X²-X²+XY]
=(X-Y)XY
(4)a³(X+3Y)-aX²(X+3Y)
◎a(X+3Y)でくくる
=a(X+3Y)[a²-X²]
◎公式 X²-Y²=(X+Y)(X-Y)
=a(X+3Y)(a+X)(a-X)
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こちらの質問も見ています😉
(3)3(3X-Y)²-6Y(3X-Y)
=3(3X-Y)(3X-Y)-6Y(3X-Y)
◎3X-Yでくくる
=(3X-Y)[3(3X-Y)-6Y]
=(3X-Y)[9X-3Y-6Y]
=(3X-Y)(9X-9Y)
◎注意!9を出せる
=9(3X-Y)(X-Y)