去括号再合并同类项(1)-(x²-2x)+(-3x+2x²) (2)-2(a²-3ab)-3(ab-2a²) 先化简再求值(1)9x+6x²-3(x-三分之二x²)其中x=-1:(2)二分之一(2x²-6x-4)-4(-1+x+四分
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![去括号再合并同类项(1)-(x²-2x)+(-3x+2x²) (2)-2(a²-3ab)-3(ab-2a²) 先化简再求值(1)9x+6x²-3(x-三分之二x²)其中x=-1:(2)二分之一(2x²-6x-4)-4(-1+x+四分](/uploads/image/z/769276-28-6.jpg?t=%E5%8E%BB%E6%8B%AC%E5%8F%B7%E5%86%8D%E5%90%88%E5%B9%B6%E5%90%8C%E7%B1%BB%E9%A1%B9%EF%BC%881%EF%BC%89-%EF%BC%88x%26%23178%3B-2x%EF%BC%89%2B%EF%BC%88-3x%2B2x%26%23178%3B%EF%BC%89+%EF%BC%882%EF%BC%89-2%EF%BC%88a%26%23178%3B-3ab%EF%BC%89-3%EF%BC%88ab-2a%26%23178%3B%EF%BC%89+%E5%85%88%E5%8C%96%E7%AE%80%E5%86%8D%E6%B1%82%E5%80%BC%EF%BC%881%EF%BC%899x%2B6x%26%23178%3B-3%EF%BC%88x-%E4%B8%89%E5%88%86%E4%B9%8B%E4%BA%8Cx%26%23178%3B%EF%BC%89%E5%85%B6%E4%B8%ADx%3D-1%EF%BC%9A%EF%BC%882%EF%BC%89%E4%BA%8C%E5%88%86%E4%B9%8B%E4%B8%80%EF%BC%882x%26%23178%3B-6x-4%EF%BC%89-4%EF%BC%88-1%2Bx%2B%E5%9B%9B%E5%88%86)
去括号再合并同类项(1)-(x²-2x)+(-3x+2x²) (2)-2(a²-3ab)-3(ab-2a²) 先化简再求值(1)9x+6x²-3(x-三分之二x²)其中x=-1:(2)二分之一(2x²-6x-4)-4(-1+x+四分
去括号再合并同类项
(1)-(x²-2x)+(-3x+2x²) (2)-2(a²-3ab)-3(ab-2a²)
先化简再求值
(1)9x+6x²-3(x-三分之二x²)其中x=-1:
(2)二分之一(2x²-6x-4)-4(-1+x+四分之一x²)其中x=5
去括号再合并同类项(1)-(x²-2x)+(-3x+2x²) (2)-2(a²-3ab)-3(ab-2a²) 先化简再求值(1)9x+6x²-3(x-三分之二x²)其中x=-1:(2)二分之一(2x²-6x-4)-4(-1+x+四分
(1)-(x²-2x)+(-3x+2x²)=-x²+2x-3x+2x²=x²-x
(2)-2(a²-3ab)-3(ab-2a²)=-2a²+6ab-3ab+6a²=4a²+3ab
(1)9x+6x²-3(x-2/3 *x²)=9x+6x²-3x+2x²=6x+8x²
其中x=-1,原式=6*(-1)+8*(-1)²=-6+8=2
(2)1/2 *(2x²-6x-4)-4(-1+x+1/4 *x²)=x²-3x-2+4-4x-x²=-7x+2
其中x=5,原式=-7*5+2=-35+2=-33
⑴原式=-x²+2x-3x+2x²
=x²-x
⑵原式=-2a²+6ab-3ab+6a²
=4a²+3ab
⑴原式=9x+6x²-3x+2x²
=6x+8x²
把x=-1代入得:
6...
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⑴原式=-x²+2x-3x+2x²
=x²-x
⑵原式=-2a²+6ab-3ab+6a²
=4a²+3ab
⑴原式=9x+6x²-3x+2x²
=6x+8x²
把x=-1代入得:
6x+8x²=-6+8
=2
⑵原式=x²-3x-2+4-4x-x²
=-7x+2
把x=5代入得:
-7x+2=-35+2
=-33
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