If x2 kx frac 16 9 is a perfect square find the... - WAEC Mathematics 2010 Question

x2 + kx + $\frac{16}{9}$; Perfect square

But, b2 - 4ac = 0, for a perfect square

where a - 1; b = k; c = $\frac{16}{9}$

k2 - 4(1) x $\frac{16}{9}$ = 0

k2 - $\frac{64}{9}$ = 0

k2 = $\frac{64}{9}$

k = $\sqrt{\frac{64}{9}}$

k = $\frac{8}{3}$