If α and β are roots of x\(^2\) + mx - n = 0, where m and n are constants, form the
equation whose roots are 1 α and 1 β .
  • A mnx\(^2\)  - n\(^2\) x - m = 0
  • B mx\(^2\)  - nx + 1 = 0
  • C nx\(^2\)  - mx + 1 = 0
  • D nx\(^2\)  - mx - 1 = 0
waec 2022furthermathematics

The correct answer is D. nx\(^2\)  - mx - 1 = 0

x\(^2\) + mx - n = 0

a = 1, b = m, c = -n

α + β = \(\frac{-b}{a}\) = \(\frac{-m}{1}\) = -m

αβ = \(\frac{c}{a}\) = \(\frac{-n}{1}\) = -n

the roots are = \(\frac{1}{α}\) and \(\frac{1}{β}\)

sum of the roots = \(\frac{1}{α}\) + \(\frac{1}{β}\)

\(\frac{1}{α}\) + \(\frac{1}{β}\) = \(\frac{α+β}{αβ}\)

α + β = -m

αβ = -n

\(\frac{α+β}{αβ}\) = \(\frac{-m}{-n}\) â†’ \(\frac{m}{n}\)

product of the roots = \(\frac{1}{α}\) * \(\frac{1}{β}\)

\(\frac{1}{α}\) + \(\frac{1}{β}\) = \(\frac{1}{αβ}\) â†’ \(\frac{1}{-n}\)

x\(^2\) - (sum of roots)x + (product of roots)

x\(^2\) - ( m/n )x + ( 1/-n ) = 0

multiply through by n

nx\(^2\) - mx - 1 = 0

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