Question

Find the vaiue(s) of k if roots of x2+kx+4=0are real

Answer 1

if the roots are real then
b^2>=4ac (where a=x b=k and c=4)
so k^2>=4*4*1
so k^2>=16
so k=4 or k=-4 --------if roots are real and equal
k>4 or k>-4 ------ if roots are real

thanks for such an interresting sum freely ask the next time for help

Answer 2

Hi ,

Compare x² + kx + 4 = 0 with

ax² + bx + c = 0

a = 1 , b = k , c = 4

If the roots are real then

discreaminant ≥ 0

b² - 4ac ≥ 0

k² - 4 × 1 × 4 ≥ 0

k² ≥ 4²

Therefore ,

k ≥ ± 4

I hope this helps you.

:)