Nonsensical sense

Algebra Level 1

Given that x x and y y are real numbers such that x + y = 24 x + y=24 and x y = 2 xy=2 , find the value of

1 x + 1 y . \frac{1}{x} + \frac{1}{y}.


The answer is 12.

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5 solutions

Victor Loh
Aug 19, 2014

We have

1 x + 1 y = x + y x y \frac{1}{x}+\frac{1}{y}=\frac{x+y}{xy}

= 24 2 = 12 , =\frac{24}{2}=\boxed{12},

and we are done.

Same way Bro and i tell you its is a very smart solution

Kushagra Sahni - 6 years, 9 months ago
Dieuler Oliveira
Aug 20, 2014

x 2 24 x + 2 = 0 x^{2}-24x+2=0

Reciprocal transformation:

2 x 2 24 x + 1 = 0 2x^{2}-24x+1=0

By Vieta's:

S = 12 . S=\boxed{12}.

Long-winded, but still a pretty good solution (at the very least interesting)

Jared Low - 6 years, 6 months ago
Ashish Menon
May 29, 2016

x + y x y = 1 x + 1 y = 24 12 = 12 \begin{aligned} \dfrac{x + y}{xy} & = \dfrac{1}{x} + \dfrac{1}{y}\\ & = \dfrac{24}{12}\\ & = \color{#69047E}{\boxed{12}} \end{aligned}

Ritam Baidya
Dec 3, 2014

simply do the LCM and solve the fraction to get 24/2 = 12

Ranjith Nrjk
Aug 16, 2014

Divide with xy on both sides

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