Question

In the Maths test two students, committed the following mistakes while solving a quadratic equation :
(i) One of them made a mistake in the constant term and got the roots as 2 and 4.
(ii) Another one committed an error in the coefficient of x and got the roots as 3 and 5.
But, they realised that they are wrong and they managed to get it right jointly. Find the correct quadratic equation.

• A. $x^2+6x+15=0$
• B. $x^2+15x-6=0$
• C. $x^2-6x+15=0$
• D. $x^2-17x+6=0$

Answer 1

The correct option is C

$x^2-6x+15=0$

Since the first person made a mistake in constant term.
Therefore, the sum of roots = 2 + 4 = 6
and the second person made a mistake in coefficient of x
Therefore, product of roots = 3 $\times$ 5 = 15
Required quadratic equation is $x^2-6x+15=0$