Question

find those values of K for which the equations x^2 - Kx - 21=0 and x^2 - 3Kx + 35 = 0 have a common root​

Answer 1

Answer:

K = 7

Step-by-step explanation:

x^2 - kx - 21 = 0

x^2 - kx + | 3 * 7 | = 0

x^2 - | 3 + 7 | - 21 = 0

So   ( x-7 ) (x+3) =  0

x^2 - 3kx + 35 = 0

x^2 - 3kx + 7 * 5 = 0

x^2 - 3 |7 + 5| x + 35 = 0

x^2 - 36 + 35 = 0

x^2 - 35 - 1 + 35 = 0

(x-35) (x-1 ) = 0

As In both Sums 7 is Common K = 7