Question

Find the least positive value of for which + + = has real

roots.​

Answer 1

Here, the given equation is,

⇒x^2

+kx+4=0

Here,

a=1, b=k, c=4

If the equation is supposed to have real roots, then D≥0. Thus,

k^2

−4×1×4≥0

k^2

≥16

k≥±4

k∈(−∞,−4]∪[4,∞)

Hence, the least positive value of k for which the equation has real roots is 4.