Question

The sum of a natural number and its positive square root is $132$. Find the number.

• A. $100$
• B. $121$
• C. $144$
• D. $81$

Answer 1

The correct option is B $121$

$x^2+x=132$

$x(x+1)=132$

$x^2+12x-11x-132=0$

$x(x+12)-11(x+12)=0$

$x=11,x=-12$

$x=-12$ it can't be considered.

$\therefore x=11$

The number is ${11}^2=121$