qqety
花朵
共回答了23个问题采纳率:95.7% 举报
(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年前
7