Question

If one root of the equation x2 -5x + k = 0 is 7, what is the other root?

Answer 1

SOLUTION :

f(x) = x² - 5x + k = 0

One root (α) = 7

other root (β) = ?

then,

as

α+β = -b/a

⇒ 7 + β = 5/1

⇒ β = 5 - 7 = -2

other Root is -2

Answer 2

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: {x}^{2} - 5x + k = 0$

$\: \: \: \: \: \: \: \: \: \: sum \: of \: zeroes = - \frac{b}{a}$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \alpha + \beta = 5$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: 7 + \beta = 5$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \beta = - 2$