规定新运算符号*的运算过程为a*b=1/3a−1/4b,则 (1)求5*(-5); (2)解方程2*(2*x)=1*x.
问题描述:
规定新运算符号*的运算过程为a*b=
a−1 3
b,则1 4
(1)求5*(-5);
(2)解方程2*(2*x)=1*x.
答
(1)5*(-5)=
×5-1 3
×(-5)=1 4
+5 3
=5 4
;35 12
(2)∵2*x=
-2 3
,x 4
∴2*(
-2 3
)=x 4
-2 3
(1 4
-2 3
)=x 4
-2 3
+1 6
=x 16
+1 2
x 16
1*x=
-1 3
,x 4
∴
+1 2
=x 16
-1 3
,x 4
去分母得,24+3x=16-12x,
移项得,15x=-8,
系数化为1得,x=-
.8 15