已知A+B-2=0,则代数式(A²-B²)-8(A²+B²)=?
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已知A+B-2=0,则代数式(A²-B²)-8(A²+B²)=?
已知A+B-2=0,则代数式(A²-B²)-8(A²+B²)=?
已知A+B-2=0,则代数式(A²-B²)-8(A²+B²)=?
A+B=2
A=2-B
(2-B)²-B²
=2²-2*2*B+B²-B²
=4-4B+2B
=4-2B
A²+B²
=(2-B)²+B²
=2²-2*2*B+B²+B²
=4-4B+2B²
=2*(2-2B+B²)
原式=(4-2B)-8*2*(2-2B+B²)
=4-2B-32+4B-16B²
=4+2B-32-16B²
=2B-28-16B²
A+B-2=0
A+B=2
(A²-B²)²-8(A²+B²) ..................题目少了一个平方
=[(A+B)(A-B)]²-8(A²+B²)
=4(A-B)²-8A²-8B²
=4A²+4B²-8A...
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A+B-2=0
A+B=2
(A²-B²)²-8(A²+B²) ..................题目少了一个平方
=[(A+B)(A-B)]²-8(A²+B²)
=4(A-B)²-8A²-8B²
=4A²+4B²-8AB-8A²-8B²
= -4(A²+B²+2AB)
= -4(A+B)²
= -4×4
= -16
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