Question

Find the value of alpha +beta - alpha * beta if alpha and beta are the roots of the equation cx^+bx+a=0

Answer 1

$if \: given \: equation \: is \: cx {}^{2} + bx + a = 0$
$let \: \alpha \: and \: \beta are \: the \: roots \: of \: the \: equation$

$then \: the \: sum \: of \: the \: roots \: \alpha + \beta = \frac{ - b}{c}$

$and \: the \: product \: of \: the \: roots \: is \: \alpha \beta = \frac{a}{c}$
$therefore \: \alpha + \beta - \alpha \beta = \frac{ - b}{c} - \frac{a}{c}$

$= - \frac{(a + b)}{c}$

hope it helps..