Applications of Quadratic Equations

Question

THE SQUARE OF A NUMBER DECREASED BY TWICE THE SAME NUMBER IS 3. WHAT IS THE NUMBER?

Answer 1

Let the number be x.

THE SQUARE OF A NUMBER DECREASED BY TWICE THE SAME NUMBER

This Means x² - 2x = 3

x² - 2x - 3 = 0.

This is a quadratic equation

x² - 3x + x -3 = 0

x(x-3) +(x-3) = 0

(x+1)(x-3) = 0

x = 3, -1

So the number is 3 or -1