3q2 = 2q + 8


(xi) 3q2 = 2q + 8
Sol. 3q2 = 2q + 8
 3q2 – 2q – 8 = 0
Comparing with aq2 + bq + c = 0 we have a = 3, b = – 2, c = – 8
b2 – 4ac = (– 2)2 – 4 (3) (– 8)
= 4 + 96
= 100
By Formula method,
q
=
-  b ± √(b2 – 4ac)




2a







∴ q
=
-(-2) ± √100




2(3)







∴ q
=
2 ±10




6







∴ q
=
2  ± 10




6







∴ q
=
2 + 10
or
2 – 10


6

6





∴ q
=
12
or
-8


6

6





∴ q
=
2
or
-4/3