用平方差公式解答(1) (4+2x)(2-x) (2) (x+二分之一)(x²+四分之一)(x-二分之一)(x的四次方+十六分之一) 先化简,后求值(1) (2x+1)(x-2)-(-3x+1)(-3x-1),其中x=-2(2) 2x²-(x+y)(x-y)-2(y+1)
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![用平方差公式解答(1) (4+2x)(2-x) (2) (x+二分之一)(x²+四分之一)(x-二分之一)(x的四次方+十六分之一) 先化简,后求值(1) (2x+1)(x-2)-(-3x+1)(-3x-1),其中x=-2(2) 2x²-(x+y)(x-y)-2(y+1)](/uploads/image/z/3806309-29-9.jpg?t=%E7%94%A8%E5%B9%B3%E6%96%B9%E5%B7%AE%E5%85%AC%E5%BC%8F%E8%A7%A3%E7%AD%94%EF%BC%881%EF%BC%89+%284%2B2x%29%282-x%29+%EF%BC%882%EF%BC%89+%EF%BC%88x%2B%E4%BA%8C%E5%88%86%E4%B9%8B%E4%B8%80%EF%BC%89%EF%BC%88x%26%23178%3B%2B%E5%9B%9B%E5%88%86%E4%B9%8B%E4%B8%80%EF%BC%89%EF%BC%88x-%E4%BA%8C%E5%88%86%E4%B9%8B%E4%B8%80%EF%BC%89%EF%BC%88x%E7%9A%84%E5%9B%9B%E6%AC%A1%E6%96%B9%2B%E5%8D%81%E5%85%AD%E5%88%86%E4%B9%8B%E4%B8%80%EF%BC%89+%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%90%8E%E6%B1%82%E5%80%BC%EF%BC%881%EF%BC%89+%EF%BC%882x%2B1%29%28x-2%29-%28-3x%2B1%29%28-3x-1%29%2C%E5%85%B6%E4%B8%ADx%3D-2%282%29+2x%26%23178%3B-%28x%2By%29%28x-y%29-2%28y%2B1%29)
用平方差公式解答(1) (4+2x)(2-x) (2) (x+二分之一)(x²+四分之一)(x-二分之一)(x的四次方+十六分之一) 先化简,后求值(1) (2x+1)(x-2)-(-3x+1)(-3x-1),其中x=-2(2) 2x²-(x+y)(x-y)-2(y+1)
用平方差公式解答
(1) (4+2x)(2-x) (2) (x+二分之一)(x²+四分之一)(x-二分之一)(x的四次方+十六分之一)
先化简,后求值
(1) (2x+1)(x-2)-(-3x+1)(-3x-1),其中x=-2
(2) 2x²-(x+y)(x-y)-2(y+1)(y-1),其中x=-2,y=-1
用平方差公式解答(1) (4+2x)(2-x) (2) (x+二分之一)(x²+四分之一)(x-二分之一)(x的四次方+十六分之一) 先化简,后求值(1) (2x+1)(x-2)-(-3x+1)(-3x-1),其中x=-2(2) 2x²-(x+y)(x-y)-2(y+1)
(1) (4+2x)(2-x)=2(2+x)(2-x)=8-2x²
(2) (x+二分之一)(x²+四分之一)(x-二分之一)
=(x+1/2)(x-1/2)(x+1/4)
=(x²-1/4)(x²+1/4)
=x⁴-1/16
先化简,后求值
(1) (2x+1)(x-2)-(-3x+1)(-3x-1),其中x=-2
=(2x+4-3)(x-2)-(3x-1)(3x+1)
=2(x+2)(x-2)-3(x-2)-(9x²-1)
=2x²-8-3x+6-9x²+1
=-7x²-3x-1
=-7*(-2)²-3*(-2)-1
=-28+6-1
=-23
(2) 2x²-(x+y)(x-y)-2(y+1)(y-1),其中x=-2,y=-1
=2x²-(x²-y²)-2(y²-1)
=x²-y²+2
=(-2)²-(-1)²+2
=3
(1) (4+2x)(2-x) =2(2+x)(2-x)=2(4-x^2)=8-2x^2
(2) (x+二分之一)(x²+四分之一)(x-二分之一)(x的四次方+十六分之一)
=(x+二分之一)(x-二分之一)(x²+四分之一)(x的四次方+十六分之一)
=(x^2-1/4)(x^2+1/4)(x^4+1/16)
...
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(1) (4+2x)(2-x) =2(2+x)(2-x)=2(4-x^2)=8-2x^2
(2) (x+二分之一)(x²+四分之一)(x-二分之一)(x的四次方+十六分之一)
=(x+二分之一)(x-二分之一)(x²+四分之一)(x的四次方+十六分之一)
=(x^2-1/4)(x^2+1/4)(x^4+1/16)
=(x^4-1/16)(x^4+1/16)
=x^8-1/256
(1) (2x+1)(x-2)-(-3x+1)(-3x-1)
=2x^2-3x-2-9x^2+1
=-7x^2-3x-1
把x=-2代入得:
原式=-7*(-2)^2-3*(-2)-1
=-28+6-1
=-23
(2) 2x²-(x+y)(x-y)-2(y+1)(y-1)
=2x^2-x^2+y^2-2y^2+2
=x^2-y^2+2
把x=-2,y=-1代入得:
原式=(-2)^2-(-1)^2+2=5
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1.(1) (4+2x)(2-x)
=2(2+x)(2-x)
=2(4-x^)
=8-2x^.
(2)(x+1/2)(x²+1/4)(x-1/2)(x^4+1/16)
= (x^-1/4)(x^+1/4)(x^4+1/16)
=(x^4-1/16)(x^4+1/16)
=x^8-1/256.
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1.(1) (4+2x)(2-x)
=2(2+x)(2-x)
=2(4-x^)
=8-2x^.
(2)(x+1/2)(x²+1/4)(x-1/2)(x^4+1/16)
= (x^-1/4)(x^+1/4)(x^4+1/16)
=(x^4-1/16)(x^4+1/16)
=x^8-1/256.
2.先化简,后求值
(1)(2x+1)(x-2)-(-3x+1)(-3x-1)
=2x^-4x+x-2-(9x^-1)
=2x^-3x-2-9x^+1
=-7x^-3x-1,
x=-2时原式=-28+6-1=-23.
(2)2x²-(x+y)(x-y)-2(y+1)(y-1)
=2x^-(x^-y^)-2(y^-1)
=2x^-x^+y^-2y^+2
=x^-y^+2,
x=-2,y=-1时原式=4-1+2=5.
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