Of the following quadratic equations, which is the one whose roots are

1.	Of the following quadratic equations, which is the one whose roots are 2 and – 15 ?(a) x2 – 2x + 15 = 0 (b) x2 + 15x – 2 = 0 (c) x2 + 13x – 30 = 0 (d) x2 – 30 = 0.
Answer» (c) x² – 13x – 30 = 0. Sum of roots = 2 + (– 15) = – 13; Product of roots = 2 × (– 15) = – 30. ∴ Required equation is x² – (sum of roots) x + product of roots = 0 ⇒ Reqd. equation = x² – 13x – 30 = 0.

Of the following quadratic equations, which is the one whose roots are 2 and – 15 ?(a) x2 – 2x + 15 = 0 (b) x2 + 15x – 2 = 0 (c) x2 + 13x – 30 = 0 (d) x2 – 30 = 0.

Answer»

(c) x² – 13x – 30 = 0.

Sum of roots = 2 + (– 15) = – 13; Product of roots = 2 × (– 15) = – 30.

∴ Required equation is x² – (sum of roots) x + product of roots = 0

⇒ Reqd. equation = x² – 13x – 30 = 0.