Question

Find the numbers such that the square of number is 15 lesser than twice the number.

• A. 8
• B. 9
• C. -3
• D. 5

Answer 1

Answer: (C), (D)

5

Let the number be $x$.
Square of number: $x^2$
Lesser by 15: $x^2-15$
of two times the number: $x^2-15=2x$

We get, $x^2-15=2x$
Lets solve, $x^2-2x-15=0x^2-5x+3x-15=0x(x-5)+3(x-5)=0(x-5)(x+3)=0\therefore x=5\&x=-3$

The number satisfying the given statement are $5\&-3$.