Question

If log x+y/5 = 1/2(log x + log y) the find the value of x/y + y/x ?​

Answer 1

Given that

log (x+y)/5 =( 1/2) {log x+logy}

We know that

log a+ log b = log ab

⇛log (x+y)/5 =( 1/2) log(xy)

We know that log a^m = m log a

⇛log (x+y)/5 = log (xy)^1/2

⇛log (x+y)/5 = log√(xy)

⇛(x+y)/5 = √(xy)

On squaring both sides then

⇛{ (x+y)/5}^2 = {√(xy)}^2

⇛(x+y)^2/5^2 = xy

⇛(x^2+y^2+2xy)/25 = xy

⇛x^2+y^2+2xy = 25xy

⇛x^2+y^2 = 25xy-2xy

⇛x^2+y^2 = 23xy

⇛( x^2+y^2)/xy = 23

⇛(x^2/xy) +(y^2/xy) = 23

⇛{(x×x)/xy} +{(y×y)/xy} = 23

⇛(x/y)+(y/x) = 23

Therefore, (x/y)+(y/x) = 23

Hence, the value of (x/y)+(y/x) is 23.