Question

Answer is
$(xy )\div (x + y)$
PLZZZ TELL ME HOW....
ITS REALLY VERY URGENT​

Answer 1

Step-by-step explanation:

4^x = 5^y = 20^z = K

4^x = K

take log both sides

xlog4 = logK

log4 = logK/ x ------(1)

similarly,

5^y = K

log5 = logK/y ------------(2)

and ,

20^z = K

z = logK/log20

= logK/log(5×4)

= logK/{ log5 + log4}

put eqns (1) and (2)

z = logK/{ logK/x + logK/y}

= 1/( 1/x + 1/y )

= xy/( x + y)

hence, z = xy/( x + y)