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If α and β are roots of x2 + mx - n = 0, ...

If α and β are roots of x2 + mx - n = 0, where m and n are constants, form the

equation whose roots are 1
α
and 1
β
.

A.

mnx2 - n2 x - m = 0

B.

mx2 - nx + 1 = 0

C.

nx2 - mx + 1 = 0

D.

nx2 - mx - 1 = 0

Correct answer is D

x2 + mx - n = 0

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

α + β = bam1 = -m

αβ = can1 = -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} → \frac{m}{n}

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

\frac{1}{α} + \frac{1}{β}\frac{1}{αβ} → \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