Answer:
Option B.
{–9 + i√225 / 24, –9 – i√225 / 24}
Step-by-step explanation:
12a² + 9a + 7 = 0
Using formula method, the solutions to the equation can be obtained as follow:
Coefficient of a² (a) = 12
Coefficient of a (b) = 9
Constant (c) = 7
a = –b ±√(b² – 4ac) / 2a
a = –9 ±√(9² – 4 × 12 × 7) / 2 × 12
a = –9 ±√(81 – 336) / 24
a = –9 ±√(– 225) / 24
Recall
–225 = –1 × 225
Thus,
–9 ±√(– 225) / 24 = –9 ±√(–1 × 225)/24
Recall
√(–1 × 225) = √–1 × √225 = i√225
Thus,
–9 ±√(–1 × 225)/24 = –9 ± i√225/24
Therefore,
a = –9 ± i√225/24
a = –9 + i√225 / 24 or –9 – i√225 / 24
Therefore, the solutions to the equation are:
{–9 + i√225 / 24, –9 – i√225 / 24}
