Question

5. Solve the equation z^2 + 4z - 9 = 0 by completing the square.

A. Z = 2 + N13
B. Z= 4 + 113
C. Z=-2 + V13
D. z = -4 + 13

Answer 1

A. Z = 2 + N13

Explanation:

Let's solve your equation step-by-step.

0=z2+4z−9

Step 1: Subtract z^2+4z-9 from both sides.

0−(z2+4z−9)=z2+4z−9−(z2+4z−9)

−z2−4z+9=0

For this equation: a=-1, b=-4, c=9

−1z2+−4z+9=0

Step 2: Use quadratic formula with a=-1, b=-4, c=9.

z=

−b±√b2−4ac

2a

z=

−(−4)±√(−4)2−4(−1)(9)

2(−1)

z=

4±√52

−2

z=−2−√13 or z=−2+√13