Question

Two students where solving a quadratic equation in $x$, one copied the constant term incorrectly and got the roots $3$ and $+2$ The other copied the constant term and the coefficient of $x^2$ correctly as $-6$ and $1$ respectively The correct roots are

• A. $3,-2$
• B. $-3,2$
• C. $-6,-6$
• D. $6,-1$

Answer 1

Answer: (D)

$6,-1$

This is the basic question from quadratic equaction

the student writes only constant term incorrectly so it will not affect the some of roots i.e. sum of roots will be same for both.

so according to concept $\frac{-b}{a}=3+2=5$

here $a=1$

so $-b=5$

hence $b=5$

now the equcation became $x^2-5x-6=0$

furthur solving we will get $(x-6)\left(x+1\right)=0$

finally roots are $6,-1$