(viii) 2n2 + 5n + 2 = 0
Sol. 2n2 + 5n + 2 = 0
Comparing with ax2 + bx + c = 0 we have a = 2, b = 5, c = 2
b2 – 4ac = (5)2 – 4 (2) (2)
= 25 – 16
= 9
By Formula method,
n
|
=
|
- b ± √(b2 – 4ac)
| ||
2a
| ||||
∴ n
|
=
|
-(5) ± √9
| ||
2(2)
| ||||
∴ n
|
=
|
-5 ± 3
| ||
4
| ||||
∴ n
|
=
|
-5 + 3
|
or
|
-5 – 3
|
4
|
4
| |||
∴ n
|
=
|
-2
|
or
|
-8
|
4
|
4
| |||
∴ n
|
=
|
- ½
|
or
|
-2
|
