Question

Find k, one of the roots of the quadratic equation kx² - 7x + 12 = 0 is 3.

Answer 1

The given quadratic equation is kx² - 7x + 12 = 0 

∴ Put x = 3

∴ k(3)² - 7(3) + 12 = 0

∴ 9k - 21 + 12 = 0

∴ 9k - 9 = 0

∴ k = `9/9`

∴ k = 1