9s2 – 4 = – 6s


(x) 9s2 – 4 = – 6s
Sol. 9s2 – 4 = – 6s
 9s2 + 6s – 4 = 0
Comparing with as2 + bs + c = 0 we have a = 9, b = 6, c = – 4
b2 – ac = (6)2 – 4 (9) (– 4)
= 36 + 144
= 180
By Formula method,
s
=
-  b ± √(b2 – 4ac)




2a







∴ s
=
-(6) ± √180




2(9)







∴ s
=
-6 ±√2× 2× 3× 3× 5




18







∴ s
=
-6  ± 6√5




18







∴ s
=
6(-1±√5)




18







∴ s
=
-1±√5




3







∴ s
=
-1 + √5
or
-1-√5


3

3