(ix) 7p2 – 5p – 2 = 0
Sol. 7p2 – 5p – 2 = 0
Comparing with ap2 + bp + c = 0 we have a = 7, b = – 5, c = – 2
b2 – 4ac = (– 5)2 – 4 (7) (– 2)
= 25 + 56
= 81
By Formula method,
p
|
=
|
- b ± √(b2 – 4ac)
| ||
2a
| ||||
∴ p
|
=
|
-(-5) ± √81
| ||
2(7)
| ||||
∴ p
|
=
|
5 ± 9
| ||
14
| ||||
∴ p
|
=
|
5 + 9
|
or
|
5 – 9
|
14
|
14
| |||
∴ p
|
=
|
14
|
or
|
-4
|
14
|
14
| |||
∴ p
|
=
|
1
|
or
|
-2/7
|
