4条解方程(比较高难度的)
(a)4的y次方等於8.求y
(b)9的(y+2)次方等於27的(y-1)次方.求y.
(c)1乘2的(y-1)次方等於1.求y
(d)2的(y+2)次方减去2的y次方等於24.