2x2 – x – 4 = 0


(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

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