Number Brain

Algebra Level 1

If the difference between two numbers is 2 and the difference of the squares of the two numbers is 6, then what is the sum of the two numbers ?

2 4 1 3 0

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3 solutions

Let the two numbers be x x and y y .
Now , According to Question.

x y = 2 \Rightarrow x-y=2 ..... ( 1 ) (1)

x 2 y 2 = 6 \Rightarrow x^2-y^2=6

( x + y ) ( x y ) = 6 (x+y)(x-y)=6

From ( 1 ) (1) .

( x + y ) ( 2 ) = 6 (x+y)(2)=6

x + y = 3 \therefore x+y=\boxed{3}

x y = 2 x-y=2 \implies 1 \boxed{1}

x 2 y 2 = 6 x^2-y^2=6 \implies 2 \boxed{2}

x 2 y 2 = ( x y ) ( x + y ) x^2-y^2=(x-y)(x+y)

6 = ( 2 ) ( x + y ) 6=(2)(x+y)

x + y = x+y= 3 \boxed{3}

Jason Chrysoprase
Jan 23, 2016

Assume, the two number is x x and y y . So x y = 2 x-y = 2 and x 2 y 2 = 6 x^2 - y^2 = 6

x 2 y 2 = 6 x^2 - y^2 = 6

( 2 + y ) 2 y 2 = 6 ( 2 + y)^2 - y^2 = 6

4 + 4 y + y 2 y 2 = 6 4 + 4y+ y^2 - y^2 = 6

4 y 2 = 0 4y-2 = 0

4 y = 2 4y = 2

y = 1 2 y = \frac{1}{2}

We have found y y , now to find x x ,

x = 2 + y x=2 + y

x = 2 + 1 2 x= 2 +\frac{1}{2}

x = 2 1 2 x = 2\frac{1}{2}

Now we sum it

x + y = 2 1 2 + 1 2 = 3 x+ y = 2\frac{1}{2} + \frac{1}{2} = 3

No need to find x and y since x + y = x 2 y 2 x y = 6 2 = 3 x+y=\dfrac{x^2-y^2}{x-y}=\dfrac{6}{2}=3

Rishabh Jain - 5 years, 4 months ago

Oh yeah, man my brain

Jason Chrysoprase - 5 years, 4 months ago

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