Question

Find the positive value of k for whichx2-8x+k=0 will have real roots.

Answer 1

k=8x-2
8x-2 should be greater than 0
x should be greater than 1/4

Answer 2

for real roots,
$d \geqslant 0$
${b}^{2} - 4ac \geqslant 0$
${( - 8)}^{2} - 4 \times 1 \times k \geqslant 0$
$64 - 4k \geqslant 0$
$64 \geqslant 4k$
$16 \geqslant k$
hence the positive value of k would be 16or less than 16