(vi) 2x2 – x – 4 = 0
Sol. 2x2 – x – 4 = 0
Comparing with ax2 + bx + c = 0 we have a = 2, b = – 1, c = – 4
b2 – 4ac = (– 1)2 – 4 (2) (– 4)
= 1 + 32
= 33
By Formula method,
x
|
=
|
- b ± √(b2 – 4ac)
| ||
2a
| ||||
∴ x
|
=
|
-(-1) ± √33
| ||
2(2)
| ||||
∴ x
|
=
|
1 ± √33
| ||
4
| ||||
∴ x
|
=
|
1+ √33
|
or
|
1 - √33
|
4
|
4
|
