玉面金牌小tt
幼苗
共回答了12个问题采纳率:91.7% 举报
1,(a-c)^2 -3(b-c)+4=(-3)^2-3(-5)+4=28
2,-x^2-xy-(3x^2-4xy+2y^2)=-4x^2+3xy-2y^2
3,-(3/2)y^2
4,x+100y
5,(x-1)^2+|y+2|=0
∴x=1;y=-2
∴(5xy-2x^2)-2(3xy-4x^2)=-10-2-2(-6-4)=8
6,3(a^2)b-[2ab^2-5(a^2b-7ab^2)+a^b]
=-2a^2b-37ab^2-a^b
=-4+148-1=143
7,个位2+3(a-1)=3a-1,百位3a-1-3=3a-4,十位a-1
所以这个数=100(3a-4)+10(a-1)+(3a-1)=313a-411
a=2,3
8,当超过10km时,价钱=10+1.8*(10-3)+2.7*(x-10)=2.7x-4.4 (x>10)
1年前
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