Question

Which of the following equations has the roots 7 and 8?

• A. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> $x^2-x+19=0$
• B. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> $x^2-19x+1=0$
• C. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> $x^2-17x+2=0$
• D. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> $x^2-15x+56=0$

Answer 1

The correct option is D <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> $x^2-15x+56=0$

Let 'A' and 'B' be the roots of a quadratic equation.

We have A=7 and B =8.

The general form of quadratic equation can be written as:

$x^2-(A+B)x+AB=0$

$\Rightarrow$ $x^2-(7+8)x+(7\times 8)=0$

$\Rightarrow$ $x^2-15x+56=0$