一、(-5x+2y)(-2y+5x)二、[(-x-1/4y)^2+(x-1/4y)^2](2x^2-1/8y^2)三、化简求值;(-2x-3)(2x-3)+(3x-2)^2+(x+1)(x+3),其中X=-1四、已知a-b=3,ab=4,求a^2+b^2的值和a^2-b^2的值
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![一、(-5x+2y)(-2y+5x)二、[(-x-1/4y)^2+(x-1/4y)^2](2x^2-1/8y^2)三、化简求值;(-2x-3)(2x-3)+(3x-2)^2+(x+1)(x+3),其中X=-1四、已知a-b=3,ab=4,求a^2+b^2的值和a^2-b^2的值](/uploads/image/z/1725667-43-7.jpg?t=%E4%B8%80%E3%80%81%28-5x%2B2y%29%28-2y%2B5x%29%E4%BA%8C%E3%80%81%5B%28-x-1%2F4y%29%5E2%2B%28x-1%2F4y%29%5E2%5D%282x%5E2-1%2F8y%5E2%29%E4%B8%89%E3%80%81%E5%8C%96%E7%AE%80%E6%B1%82%E5%80%BC%EF%BC%9B%28-2x-3%29%282x-3%29%2B%283x-2%29%5E2%2B%28x%2B1%29%28x%2B3%29%2C%E5%85%B6%E4%B8%ADX%3D-1%E5%9B%9B%E3%80%81%E5%B7%B2%E7%9F%A5a-b%3D3%2Cab%3D4%2C%E6%B1%82a%5E2%2Bb%5E2%E7%9A%84%E5%80%BC%E5%92%8Ca%5E2-b%5E2%E7%9A%84%E5%80%BC)
一、(-5x+2y)(-2y+5x)二、[(-x-1/4y)^2+(x-1/4y)^2](2x^2-1/8y^2)三、化简求值;(-2x-3)(2x-3)+(3x-2)^2+(x+1)(x+3),其中X=-1四、已知a-b=3,ab=4,求a^2+b^2的值和a^2-b^2的值
一、(-5x+2y)(-2y+5x)
二、[(-x-1/4y)^2+(x-1/4y)^2](2x^2-1/8y^2)
三、化简求值;(-2x-3)(2x-3)+(3x-2)^2+(x+1)(x+3),其中X=-1
四、已知a-b=3,ab=4,求a^2+b^2的值和a^2-b^2的值
一、(-5x+2y)(-2y+5x)二、[(-x-1/4y)^2+(x-1/4y)^2](2x^2-1/8y^2)三、化简求值;(-2x-3)(2x-3)+(3x-2)^2+(x+1)(x+3),其中X=-1四、已知a-b=3,ab=4,求a^2+b^2的值和a^2-b^2的值
1.
(-5x+2y)(-2y+5x)
=-(5x-2y)(5x-2y)
=-(5x-2y)^2
=-(25x^2-20xy+4y^2)
=20xy-25x^2-4y^2
2.
[(-x-1/4y)^2+(x-1/4y)^2](2x^2-1/8y^2)
=[(x+1/4y)^2+(x-1/4y)^2](2x^2-1/8y^2)
=(x^2+1/2y+1/16y^2+x^2-1/2y+1/16y^2)(2x^2-1/8y^2)
=(2x^2+1/8y^2)(2x^2-1/8y^2)
=4x^4-1/64y^4
3.
(-2x-3)(2x-3)+(3x-2)^2+(x+1)(x+3)
=(3+2x)(3-2x)+(3x-2)^2+(x+1)(x+3)
=9-4x^2+9x^2-6x+4+x^2+3x+x+3
=6x^2-2x+16
=2(x^2-x+8)
=2*(1+1+8)
=20
4.
a^2+b^2
=(a^2+b^2-2ab)+2ab
=(a-b)^2+2ab
=9+8
=17
(a+b)^2
=(a-b)^2+4ab
=9+16
=25
a+b=5或a+b=-5
a^2-b^2
=(a+b)(a-b)
=15或-15
1.-25x^2+20xy-4y^2
2.(2x^2+1/8y^2)(2x^2-1/8y62)=4x^4-1/64y^4
3.-4x^2+9+9x^2-12x+4+x^2+4x+3
=6x^2-8x+16
=6+8+16=30
4.a^2+b^2=(a-b)^2+2ab=9+8=17
∵(a+b)^2=(a-b)^2+4ab=9+16=25, a+b=±5
a^2-b^2=(a+b)(a-b)=±15