The quadratic equation 7x²+bx+5=0 has two complex roots. What are the possible values of b?
complex roots means a negative discriminant ... b^2 - 4 a c < 0
b^2 - (4 * 7 * 5) < 0 ... b^2 < 140 ... -2√35 < b < 2√35
b^2 - (4 * 7 * 5) < 0 ... b^2 < 140 ... -2√35 < b < 2√35