(vii) 3y2 + 7y + 4 = 0
Sol. 3y2 + 7y + 4 = 0
Comparing with ax2 + bx + c = 0 we have a = 3, b = 7, c = 4
b2 – 4ac = (7)2 – 4 (3) (4)
= 49 – 48
= 1
By Formula method,
y
|
=
|
- b ± √(b2 – 4ac)
| ||
2a
| ||||
∴ y
|
=
|
-(7) ± √1
| ||
2(3)
| ||||
∴ y
|
=
|
-7 ± 1
| ||
6
| ||||
∴ y
|
=
|
-7 + 1
|
or
|
-7 – 1
|
6
|
6
| |||
∴ y
|
=
|
-6
|
or
|
-8
|
6
|
6
| |||
∴ y
|
=
|
-1
|
or
|
-4/3
|
