Question

Find the value(s) of k dor which the equation x2+5kx+16=0 has real and equal roots.

Answer 1

$d = {b}^{2} - 4ac \\ where \: a = 1. \: b = 5k \:. c = 16 \\ d = {5k}^{2} - 4(1)(16) \\ {25k }^{2} - 64 = 0 \\ {25k}^{2} = + 64 \\ {k }^{2} = \frac{64}{25} \\ k = \sqrt{ \frac{64}{25} } \\ k = \frac{8}{5} {ans}$