数学题计算(2x+Y-z+5)(2x-y+z+5)等于
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数学题计算(2x+Y-z+5)(2x-y+z+5)等于
还有(a+3b+2c)(a-3b+6c)等于多少
还有(a+3b+2c)(a-3b+6c)等于多少
(2x+Y-z+5)(2x-y+z+5)
=[(2x+5)+(y-z)][(2x+5)-(y-z)]
=(2x+5)²-(y-z)²
=4x²+20x+25-(y²-2yz+z²)
=4x²+20x+25-y²+2yz-z²
(a+3b+2c)(a-3b+6c)
=a(a-3b+6c)+3b(a-3b+6c)+2c(a-3b+6c)
=a²-3ab+6ac+3ab-9b²+18bc+2ac-6bc+12c²
=a²+8ac-9b²+12bc+12c²
=[(2x+5)+(y-z)][(2x+5)-(y-z)]
=(2x+5)²-(y-z)²
=4x²+20x+25-(y²-2yz+z²)
=4x²+20x+25-y²+2yz-z²
(a+3b+2c)(a-3b+6c)
=a(a-3b+6c)+3b(a-3b+6c)+2c(a-3b+6c)
=a²-3ab+6ac+3ab-9b²+18bc+2ac-6bc+12c²
=a²+8ac-9b²+12bc+12c²
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