Question

Find a value of k such that kx^2 + 12x − 4 = 0 has one real-number solution. Explain.

Answer 1

For one and only 1 real solution, the discriminant = 0 (see chart attached) 
So we know b^2-4ac=0 when the equation is in the format of ax^2+bx-c=0. Make sure your equation is in the right format first!

Given kx^2+12x-4=0 
b=12 
so b^2-4ac=0 
144 = 4ac 
144 = 4(k)(-4) 
144/(-16) = k 
k = -9