Determine the value of k so that the two roots of the equation x2 − kx + 36 = 0 are equal.
We know that roots of the quadratic equation is equal when D = 0
⇒b2−4ac=0
So, from the equation x2 − kx + 36 = 0
a = 1, b = -k and c = 36
⇒ k2−4(ac)=0
k2−4(36)=0
k2=144
∴ k = 12 or -12