2n2 + 5n + 2 = 0


(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