1.2x(x-5)-(x+3)(x-2) 2.(-3xy²)²·(-xy)三次方3.(1/9)负一次方+(-2)三次方+3-(1-π)º4.(2x-1)²+(1-3x)²=13(x-1)(x+1)求x的值5.已知:x+y=-6,xy=2,求代数式(x-y)²的值,为______?
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1.2x(x-5)-(x+3)(x-2) 2.(-3xy²)²·(-xy)三次方3.(1/9)负一次方+(-2)三次方+3-(1-π)º4.(2x-1)²+(1-3x)²=13(x-1)(x+1)求x的值5.已知:x+y=-6,xy=2,求代数式(x-y)²的值,为______?
1.2x(x-5)-(x+3)(x-2) 2.(-3xy²)²·(-xy)三次方
3.(1/9)负一次方+(-2)三次方+3-(1-π)º
4.(2x-1)²+(1-3x)²=13(x-1)(x+1)求x的值
5.已知:x+y=-6,xy=2,求代数式(x-y)²的值,为______?
1.2x(x-5)-(x+3)(x-2) 2.(-3xy²)²·(-xy)三次方3.(1/9)负一次方+(-2)三次方+3-(1-π)º4.(2x-1)²+(1-3x)²=13(x-1)(x+1)求x的值5.已知:x+y=-6,xy=2,求代数式(x-y)²的值,为______?
1.
2x(x-5) - (x+3)(x-2)
= 2x² - 10x - (x² + x - 6)
= x² - 11x + 6
2.
(-3xy²)² × (-xy)^3
= 9x²y^4 × (-x^3y^3)
= -9(x^5)(y^7)
3.
(1/9)^(-1) + (-2)^3 + 3 - (1-π)º
= 9 -8 + 3 - 1
= 3
4.
(2x-1)²+(1-3x)²=13(x-1)(x+1)
展开得:
(4x² - 4x + 1) + (9x² - 6x + 1) = 13(x² - 1)
即13x² - 10x + 2 = 13x² - 13
所以10x = 15
解得x = 1.5
5.
(x-y)²
= x² + y² - 2xy
= (x+y)² - 4xy
= 36 - 8 = 28
希望有用.
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