Question

The difference of the square of a number and 28 is equal to 3 times that number find the positive solution

Answer 1

The required positive number is 7.

Step-by-step explanation:

Let the number = x

To find, the positive number = ?

According to question,

$x^{2}-28=3x$

⇒ $x^{2}$ - 3x - 28 = 0

By Factorisation method,

⇒ $x^{2}$ - 7x + 4x - 28 = 0

⇒ x(x - 7) + 4(x - 7) = 0

⇒ (x - 7)(x + 4) = 0

⇒ x - 7 = 0 or, x + 4 = 0

⇒ x  = 7 or, x = - 4 [ - 4 is a negative number)

⇒ x  = 7

Thus, the required positive number is 7.