化簡式子↓
(1)5x的負1次方*y，分之3a的負2次方 = ?

另外一題: 設67的x次方 = 27 ，603的y次方=81 ，
則x分之3 - y分之4 = ?


(1)的答案是5a的平方*y分之3x
另外一提的答案是 -2
我需要祥解謝謝

(1)
定義a^(-b) = 1/(a^b)

由此可得[3a^(-2)] / [5x^(-1)] = (3/5)*[a^(-2) / x^(-1)] = (3/5)*(x / a^2) = (3x) / (5a^2)

(2)

67^x = 27 → x*log67 = 3*log3 → 3/x = log67 / log3.....(第一式)
603^y = 81 → y*log603 = 4*log3
→ y*[(log67)+(2*log3)] = 4*log3
→ 4/y = (log67 / log3) + 2.....(第二式)

將第一式和第二式代入 3/x - 4/y = (log67 / log3) - [(log67 / log3) + 2] = -2