+0

0
120
1

he quadratic equation 2x^2 + bx + 18 = x^2 + 9 has a double root. Find all possible values of b.

Apr 2, 2022

#1
+2
+1

A quadratic has a double root when the discriminant $$b^2-4ac$$ is equal to $$0$$.

~

Rearraging the equation grants $$x^2+bx+9=0 \Longrightarrow$$ $$a = 1, b = b, c = 9$$

~

$$b^2 - 4(1)(9) = 0$$

$$b^2 = 36\\ b = \boxed{\pm 6}$$

Apr 2, 2022