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Question
Find the discriminant of the following equations and hence find the nature of roots: 2x2– 3x + 5 = 0
Solution
2x2– 3x + 5 = 0
Here a = 2, b = -3, c = 5
∴ D - b2 - 4ac
= (-3)2 - 4 x 2 x 5
= 9 - 40
= -31
∴ Discriminant = -31
∵ D < 0,
∴ Roots are not real.
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Solution :
Compare x2 + 2x – 9 = 0 with ax2 + bx + c = 0
a = 1, b = 2, c = `square`
∴ b2 – 4ac = (2)2 – 4 × `square` × `square`
Δ = 4 + `square` = 40
∴ b2 – 4ac > 0
∴ The roots of the equation are real and unequal.
