问题
解答题
计算与化简 (1)计算:-24÷[1-(-3)2]+(
(2)先化简,再求值:3x+6x2-3(
(3)解方程:5(x-
(4)解方程:
|
答案
(1)-24÷[1-(-3)2]+(
-2 3
)×(-15)3 5
=-16÷[1-9]+(-10+9)
=-16÷[-8]-1
=2-1
=1;
(2)3x+6x2-3(
x2+x)2 3
=3x+6x2-2x2-3x
=4x2,
当x=-5时,原式=4×(-5)2=100;
(3)5(x-
)=2 3
+(x-4 3
)2 3
4(x-
)=2 3
,4 3
x-
=2 3
,1 3
x=1;
(4)
+0.5x+0.9 0.5
=x-5 3
,0.01+0.02x 0.03
原方程化为
+5x+9 5
=x-5 3
,1+2x 3
去分母,得3(5x+9)+5(x-5)=5(1+2x),
化简,得10x=3,
解得x=
.3 10