1.化简:(5a²+2a-1)-4(3-8a+2a²)2.化简再求值½-2(x-三分之一y²)+(-三分之二x+三分之一y²),x=-3,y=二分之三3.解方程3x+x-1/2=3-2x-1/3
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![1.化简:(5a²+2a-1)-4(3-8a+2a²)2.化简再求值½-2(x-三分之一y²)+(-三分之二x+三分之一y²),x=-3,y=二分之三3.解方程3x+x-1/2=3-2x-1/3](/uploads/image/z/1107665-17-5.jpg?t=1.%E5%8C%96%E7%AE%80%EF%BC%9A%285a%26%23178%3B%2B2a-1%29-4%283-8a%2B2a%26%23178%3B%292.%E5%8C%96%E7%AE%80%E5%86%8D%E6%B1%82%E5%80%BC%26%23189%3B-2%EF%BC%88x-%E4%B8%89%E5%88%86%E4%B9%8B%E4%B8%80y%26%23178%3B%EF%BC%89%2B%EF%BC%88-%E4%B8%89%E5%88%86%E4%B9%8B%E4%BA%8Cx%2B%E4%B8%89%E5%88%86%E4%B9%8B%E4%B8%80y%26%23178%3B%EF%BC%89%2Cx%3D-3%2Cy%3D%E4%BA%8C%E5%88%86%E4%B9%8B%E4%B8%893.%E8%A7%A3%E6%96%B9%E7%A8%8B3x%EF%BC%8Bx-1%2F2%3D3-2x-1%2F3)
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1.化简:(5a²+2a-1)-4(3-8a+2a²)2.化简再求值½-2(x-三分之一y²)+(-三分之二x+三分之一y²),x=-3,y=二分之三3.解方程3x+x-1/2=3-2x-1/3
1.化简:(5a²+2a-1)-4(3-8a+2a²)
2.化简再求值½-2(x-三分之一y²)+(-三分之二x+三分之一y²),x=-3,y=二分之三
3.解方程3x+x-1/2=3-2x-1/3
1.化简:(5a²+2a-1)-4(3-8a+2a²)2.化简再求值½-2(x-三分之一y²)+(-三分之二x+三分之一y²),x=-3,y=二分之三3.解方程3x+x-1/2=3-2x-1/3
1 (5a²+2a-1)-4(3-8a+2a²)
=5a²+2a - 1 - 12 +32a -8a²
= -3a² + 34a - 13
2 ( ½)-2(x-y²/3)+[-(2/3)x+(1/3)y²]
=(1/2) - 2x + (2/3)y² -(2/3)x + (1/3)y²
= (1/2)-(8/3)x + y²
当 x = -3 y = 3/2时
原式= (1/2) - (8/3)x + y²= (1/2) - (8/3)×(-3) + (3/2)² = -21/4
3 3x + x - 1/2 = 3 - 2x - 1/3
移项得 3x + x + 2x = 3 - 1/3 + 1/2
合并同类项得 6x = 19/6
两边同时除以6得 x = 19/36