The mean proportional of `a\ a n d\ b` is 10 and the value of `a` is four times the value of `bdot` the value of `a+b(a >0, b >0)` is 20 (b) 25 101 (d) 29

Options

A. 20
B. 25
C. 101
D. 29

Answer

B

Explanation

Given, `10^(2) = a xx b " " (1)`
rArr 100 = ab
` "and a"=4b " " (2)`
From Eqs (1) and (2), 100 = `4b^(2)`
`rArr b = 5 " and "a = 20`
`therefore a + b = 25`
Hence, the correct option is (b).