Question

Suppose that two persons $A$ and $B$ solve the equation ${{x}^{2}}+ax+b=0$ . While solving $A$ commits a mistake in the coefficient of $x$ was taken as $15$ in place of $-9$ and finds the roots as $-7$ and $-2$ . Then, the equation is

• A. ${{x}^{2}}+9x+14=0$
• B. ${{x}^{2}}-9x+14=0$
• C. ${{x}^{2}}+9x-14=0$
• D. ${{x}^{2}}-9x-14=0$

Answer 1

Answer: (B)

${{x}^{2}}-9x+14=0$

Answer 2

Let the incorrect equation is ${{x}^{2}}+15x+b=0$ .
Since, roots are $-7$ and $-2$ .
$\therefore$ Product of roots, $b=14$
So, correct equation is ${{x}^{2}}-9x+14=0$