Question

If $f\left(x\right)=x^2-7x+12$, then find its zero(es)

• A. $3$ and $4$
• B. $2$ and $3$
• C. $1$ and $2$
• D. $4$ and $5$

Answer 1

The correct option is A $3$ and $4$

$f\left(x\right)=x^2-7x+12$
To find the zero(es) of above polynomial, let us equate it to zero.
$f\left(x\right)=0$
$\Rightarrow x^2-7x+12=0$
$\Rightarrow x^2-(3x+4x)+12=0$
$\Rightarrow x^2-(3+4)x+12=0$
$x^2-3x-4x+12=0$
$x(x-3)-4(x-3)=0$
$(x-4)(x-3)=0$
$\Rightarrow x-4=0$ or $x-3=0$
$x=4,x=3$
Hence, $4$ and $3$ are the zeroes of given polynomials.
So, the correct answer is option (a)