问题
解答题
先化简,再求值: (1)6x2+9x-3(x-
(2)已知:x-y=3,x-z=
|
答案
(1)原式=6x2+9x-3x+2x2=8x2+6x,
∵x=-2,
∴原式=8×4+6×(-2)=20;
(2)y-z=x-z-(x-y)=
-3=-21 3
.2 3
先化简,再求值: (1)6x2+9x-3(x-
(2)已知:x-y=3,x-z=
|
(1)原式=6x2+9x-3x+2x2=8x2+6x,
∵x=-2,
∴原式=8×4+6×(-2)=20;
(2)y-z=x-z-(x-y)=
-3=-21 3
.2 3