The product of two successive integral multiples of 5 is 300. Determine the multiples.

Question

Philoid · Accepted Answer

Let the successive integral multiples of 5 be a, a + 5.

⇒ a(a + 5) = 300

⇒ a² + 5a – 300 = 0

⇒ a² + 20a – 15a – 300 = 0

⇒ a(a + 20) – 15(a + 20) = 0

⇒ (a + 20)(a - 15) = 0

⇒ a = - 20, 15

Numbers are, -20, -15 or 15, 20