(1)(2x²-7x+5)+(3x-1)-(x²-1) (2)x-3(1-2x+x²)+3(-2+3x-x²) (3)3a+二分之一(a-6b)-三(4)5a+(-2a)+｛a+1+(2a+a)+[a+1-(a+3)]｝

(1)(2x²-7x+5)+(3x-1)-(x²-1) (2)x-3(1-2x+x²)+3(-2+3x-x²) (3)3a+二分之一(a-6b)-三(4)5a+(-2a)+｛a+1+(2a+a)+[a+1-(a+3)]｝
(1)(2x²-7x+5)+(3x-1)-(x²-1) (2)x-3(1-2x+x²)+3(-2+3x-x²) (3)3a+二分之一(a-6b)-三
(4)5a+(-2a)+｛a+1+(2a+a)+[a+1-(a+3)]｝

(1)(2x²-7x+5)+(3x-1)-(x²-1) (2)x-3(1-2x+x²)+3(-2+3x-x²) (3)3a+二分之一(a-6b)-三(4)5a+(-2a)+｛a+1+(2a+a)+[a+1-(a+3)]｝
(1)(2x²-7x+5)+(3x-1)-(x²-1)
=2x^2-7x+5+3x-1-x^2+1
=x^2-4x+5
(2)x-3(1-2x+x^2)+3(-2+3x-x^2)
=x-3+6x-3x^2-6+9x-3x^2
=-6x^2+16x-9
(3)3a+1/2(a-6b)-3
=3a+1/2a-3b-3
=7/2a-3b-3
(4)5a+(-2a)+｛a+1+(2a+a)+[a+1-(a+3)]｝
=3a+(4a+1+a+1-a-3)
=3a+4a-1
=7a-1

1. 2x 2;-7x+5 = 0 2 -5 1 -1 (2x-5)(x-1) = 0 , x = 5/2 , 1 2. 怎么有个Y？ 3. (2x-3) 2;-2x+3 = 0 (2x-