(xi) 3q2 = 2q + 8
Sol. 3q2 = 2q + 8
3q2 – 2q – 8 = 0
Comparing with aq2 + bq + c = 0 we have a = 3, b = – 2, c = – 8
b2 – 4ac = (– 2)2 – 4 (3) (– 8)
= 4 + 96
= 100
By Formula method,
q
|
=
|
- b ± √(b2 – 4ac)
| ||
2a
| ||||
∴ q
|
=
|
-(-2) ± √100
| ||
2(3)
| ||||
∴ q
|
=
|
2 ±10
| ||
6
| ||||
∴ q
|
=
|
2 ± 10
| ||
6
| ||||
∴ q
|
=
|
2 + 10
|
or
|
2 – 10
|
6
|
6
| |||
∴ q
|
=
|
12
|
or
|
-8
|
6
|
6
| |||
∴ q
|
=
|
2
|
or
|
-4/3
|
