Question

If a + b = 3 and a +B3 = 7, then a and B are the roots of
(a) 3x² + 9x + 7 - 0
(b) 9x? – 27 x + 20 = 0
(c) 2x6x +15 = 0
(d) none of these​

Answer 1

$\sf If\:A \:and \:B\: are\: the \:roots \:of \:the\\\sf quadratic \:equation \:</p><p>ax^2+bx+c=0,then\\\sf </p><p>A+B= \frac{-b}{a}\\\sf </p><p>In \:the \:question, \\\sf </p><p>A+B=3=\frac{-(-27)}{9}\\\sf </p><p>Hence,\:the\: correct \:answer \:is \\9x^2 – 27 x + 20 = 0$