What is the third proportional of (x² - y²) and (x – y) ?

Correct Answer is : x−yx+yx-y/x+yx+yx−y

Correct Answer is : x−yx+yx-y/x+yx+yx−y

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RRB Group-D Model Paper 16 with answers for online practice

Question : 40 of 100

Marks: +1, -0

(x^2 - y^2)

and (x – y) ?

Solution:

Concept:

If 3 number A, B, and C are in proportion then

A/B = B/C

Where A, B, C are first, second, and third proportion respectively.Calculation:

Let the

3^{rd}

proportional be A

∴

(x^2 - y^2)

/(x -y) = (x - y)/A

⇒ A =

\frac{(x - y)^2}{x^2 - y^2}

Now,

x^2 - y^2

= (x – y)(x+y)

⇒A=

\frac{(x-y)(x-y)}{(x-y)(x+y)}

⇒A=

\frac{(x-y)}{(x+y)}

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