Use the quadratic formula to solve the quadratic equation X2

Use the quadratic formula to solve the quadratic equation. X^2 + 11x + 28 = 0 4, 7 28, 0 -4, -7 4, -7

Solution

6. x² + 11x +28 = 0 . Therefore, x = [ -11 ± { (11)² - 4(1)(28) } ] / 2*1 = [ -11 ± ( 121 – 112)]/2 = ( -11± 9 )/2 = ( -11 ± 3)/2. Therefore, either x = (-11+ 3)/2 = -8/2 = - 4 or, x = ( -11 -3)/2 = -14/2 = -7 . The answer is B.

7. 7m² + 10m + 2= 0 Therefore, m = [ -10 ± { (10)² - 4(7)(2) } ] / 2*7 = [ -10 ± ( 100 – 56)]/14 =( -10 ± 44 )/14 = ( -10 ± 211 )/2 =( -5± 11)/ 7. The answer is C.

8. 3m² + 8m + 2 = 0 . Therefore, m = [ -8 ± { (8)² - 4(3)(2) } ] / 2*3 = [ - 8 ± ( 64 – 24)]/6 = ( -8 ± 40 )/6 = ( -8 ± 210 )/6 = ( -4 ± 10)/ 3. The answer is D.