Question

KM is a straight line of 13 units If K has the coordinate (2, 5) and M has the coordinates (x, – 7) find the possible value of x.

Answer 1

Using distance formula
(x₂ - x₁)² + (y₂ - y₁)² = d²
⇒ (x - 2)² + (-7 - 5)² = 13²
⇒ x² - 4x + 4 + 144 = 169
⇒ x² - 4x + 148 - 169 = 0
⇒ x² - 4x - 21 = 0
⇒ x² - 7x + 3x - 21 = 0
⇒ (x - 7) +3 (x - 7) = 0
⇒ (x + 3) (x - 7) = 0
x = 7, -3.