牧雍
幼苗
共回答了22个问题采纳率:81.8% 举报
4(a-2b)^2-9(2a+b)^2
=(2a‘-4b)²-(6a+3b)²
=(2a-4b+6a+3b)(2a-4b-6a-3b)
=(8a-b)(-4a-7a)
1/2x^2-2xy^2+2y^4
=(1/2)(x²-4xy+4y²)
=(1/2)(x-2y)²
16x^4-(4-8x)^2
=(2x)^4-(4-8x)²
=[(2x)²+(4-8x)][(2x)²-(4-8x)]
=(4x²-8x+4)(4x²+8x-4)
=16(x²-2x+1)(x²+2x-1)
=16(x-1)²(x²+2x-1)
a^2+b^2+2ab+2a+2b+1
=(a^2+b^2+2ab)+(2a+2b)+1
=(a+b)²+2(a+b)+1
=(a+b+1)²
将x-1/x=3两边平方,得,
x²-2+1/x²=9
即x^2+1/x^2=9+2=11
1年前
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