计算题, 初二数学作业,整式的乘除,,解答详细点,,
3个回答
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(34) (-3x+2y-z)(3x+2y+z)
=-9x²-6xy-3xz+6xy+4y²+2yz-3xz-2yz-z²
=-9x²+4y²-z²-6xz
(35) (a-2b+3)²
=(a-2b+3)(a-2b+3)
=a²-2ab+3a-2ab+4b²-6b+3a-6b+9
=a²+4b²-4ab+6a-12b+9
(36) (a+b)(a-b)+(a-b)²-2b²
=a²-b²+a²-2ab+b²-2b²
=2a²-2ab
(37) 3(x-2)²+2(3-x)
=3(x²-4x+4)+6-2x
=3x²-12x+12+6-2x
=3x²-14x+18
=-9x²-6xy-3xz+6xy+4y²+2yz-3xz-2yz-z²
=-9x²+4y²-z²-6xz
(35) (a-2b+3)²
=(a-2b+3)(a-2b+3)
=a²-2ab+3a-2ab+4b²-6b+3a-6b+9
=a²+4b²-4ab+6a-12b+9
(36) (a+b)(a-b)+(a-b)²-2b²
=a²-b²+a²-2ab+b²-2b²
=2a²-2ab
(37) 3(x-2)²+2(3-x)
=3(x²-4x+4)+6-2x
=3x²-12x+12+6-2x
=3x²-14x+18
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