Question

Find the value of k, for which one root of quadratic equation kx²-14x+8=0 is 2

Answer 1

If one root is 2 then

k(2)^2 - 14(2) + 8 = 0

4k - 28 + 8 = 0

4k = 28 - 8

4k = 20

k = 5 (answer)

Answer 2

k = 5

since x = 2 is a root then f(2) = 0

substitute x = 2 into the equation

4k - 28 + 8 = 0

4k - 20 = 0 ( add 20 to both sides )

4k = 20 ( divide both sides by 4 )

k = 5