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
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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