整式运算:(1)已知x-y=-2,x²+y²=34.求①xy ②x+y ③x²-y²(2)代数式(2x-1)(x²+6)-x²(2x+3)+(2x-3)²的值为?
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![整式运算:(1)已知x-y=-2,x²+y²=34.求①xy ②x+y ③x²-y²(2)代数式(2x-1)(x²+6)-x²(2x+3)+(2x-3)²的值为?](/uploads/image/z/15189243-51-3.jpg?t=%E6%95%B4%E5%BC%8F%E8%BF%90%E7%AE%97%EF%BC%9A%EF%BC%881%EF%BC%89%E5%B7%B2%E7%9F%A5x-y%3D-2%2Cx%26%23178%3B%2By%26%23178%3B%3D34.%E6%B1%82%E2%91%A0xy+%E2%91%A1x%2By+%E2%91%A2x%26%23178%3B-y%26%23178%3B%EF%BC%882%EF%BC%89%E4%BB%A3%E6%95%B0%E5%BC%8F%282x-1%29%28x%26%23178%3B%2B6%29-x%26%23178%3B%282x%2B3%29%2B%282x-3%29%26%23178%3B%E7%9A%84%E5%80%BC%E4%B8%BA%3F)
整式运算:(1)已知x-y=-2,x²+y²=34.求①xy ②x+y ③x²-y²(2)代数式(2x-1)(x²+6)-x²(2x+3)+(2x-3)²的值为?
整式运算:(1)已知x-y=-2,x²+y²=34.求①xy ②x+y ③x²-y²
(2)代数式(2x-1)(x²+6)-x²(2x+3)+(2x-3)²的值为?
整式运算:(1)已知x-y=-2,x²+y²=34.求①xy ②x+y ③x²-y²(2)代数式(2x-1)(x²+6)-x²(2x+3)+(2x-3)²的值为?
一、
1)x-y=-2
(x-y)²=4
x²-2xy+y²=4
x²+y²=34.
则34-2xy=4
xy=15
2)x²+y²=34.
x²+2xy+y²-2xy=34
(x+y)²-2*15=34
(x+y)²=64
x+y=±8
3)
x²-y²=(x+y)(x-y)
当x+y=8时 x²-y²=(x+y)(x-y)=8*(-2)=-16
当x+y=-8时 x²-y²=(x+y)(x-y)=(-8)*(-2)=16
二、(2x-1)(x²+6)-x²(2x+3)+(2x-3)²
=2x³+12x-x²-6-2x³-3x²+4x²-12x+9
=3