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標題:
發問:
請將下列算式分解: 28(x加y)既2次方 減7(x-y)既2次方
最佳解答:
28(x加y)既2次方 減7(x-y)既2次方 =28(x加y)(x加y) -7(x-y)(x-y) =28(x既2次方+xy+xy+y既2次方)-7(x既2次方-xy-xy+y既2次方) =28x既2次方+56xy+28y既2次方-7x既2次方+14xy-7y既2次方 =21x既2次方+70xy+21y既2次方 =(3x+y)(7x+21y)
其他解答:
28(x+y)^2 - 7(x-y)^2 = 7[4(x+y)^2 - (x-y)^2] =7[2^2 (x+y)^2 - (x-y)^2] =7(2x+2y-x+y)(2x+2y+x-y) = 7(x+3y)(3x+y)
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(f3數學功課)因式分解問題發問:
請將下列算式分解: 28(x加y)既2次方 減7(x-y)既2次方
最佳解答:
28(x加y)既2次方 減7(x-y)既2次方 =28(x加y)(x加y) -7(x-y)(x-y) =28(x既2次方+xy+xy+y既2次方)-7(x既2次方-xy-xy+y既2次方) =28x既2次方+56xy+28y既2次方-7x既2次方+14xy-7y既2次方 =21x既2次方+70xy+21y既2次方 =(3x+y)(7x+21y)
其他解答:
28(x+y)^2 - 7(x-y)^2 = 7[4(x+y)^2 - (x-y)^2] =7[2^2 (x+y)^2 - (x-y)^2] =7(2x+2y-x+y)(2x+2y+x-y) = 7(x+3y)(3x+y)
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