If one of the roots of the quadratic equation ` 7 x^(2) - 50 x + k = 0 ` is 7, then is the value of k ?

Options

A. 7
B. 1
C. `(50)/(7)`
D. `(7)/(50)`

Answer

A

Explanation

The given equation is ` 7 x^(2) - 50 x + k = 0 `
Here, a = 7 , b =- 50, c = k
`:. alpha + beta = - (b)/(a)`
`:. alpha beta = (50)/(7)`
or ` beta = (50)/(7) - 7`
`rArr beta = (1)/(7) " " ` [ `:. alpha = 7 ` (given) ]
and ` alpha beta = (c) /(a) rArr 7 xx (1)/(7) = (k)/( 7)`
k = 7