Q3 of 83 Page 76

Find k, if one of the roots of x2 — kx + 6 = 0 is 3.

One of the root of equation x2 — kx + 6 = 0 is 3 which means x = 3 is a root


As x = 3 is a root of x2 — kx + 6 = 0 hence x = 3 will satisfy the equation x2 — kx + 6 = 0


Put x = 3 in equation x2 — kx + 6 = 0


⇒ 32 – k × (3) + 6 = 0


⇒ 9 – 3k + 6 = 0


⇒ 15 – 3k = 0


⇒ 15 = 3k


⇒ k =


⇒ k = 3


More from this chapter

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3

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 3

If x = —1 is a root of x2 — px + q = 0, p, q ∈ R, prove that p + q + 1 = O.

 3

Find k, if one of the roots of x2 + 3(k + 2)x — 9 = 0 is —3.

 4

Solve the following equations using the method of factorization:

27x2 — 48 = 0