Ratio and Proportion, Indicies and logrithm Part-6

29) Simplification of (x^m+3n .x^4m-9n ) / x^{6m-6n        (a)} x^{m        (b)} x ^{-m         (c)} xⁿ        (d) x^-n

30) The ages of two persons are inthe ratio 5:7 .       Eighteen years ago their ages were in the        ratio of 8:13, their present ages (in years) are :      (a) 50, 70      (b) 70, 50      (c) 40, 56      (d) None

³¹⁾ If 4^x = 5^y = 20^z then z is equal to :      (a) xy      (b) (x+y) / xy      (c) 1/xy      (d) xy/ (x +y)

32) log₄  (x² +x) – log₄  (x +1)  = 2        Find x :      (a) 16      (b) 0      (c) -1      (d) None of these