Algebraic Algebra

Algebra Level pending

Let x x and y y be positive integers satisfying

3 x + 2 y + 4 x + 3 y = 11 z 3x + 2y + 4x +3y = 11z

with z = 3 z=3 .

What are the values of x x and y y ?

Submit your answer as the two-digit integer, x y \overline{xy} .


The answer is 41.

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4 solutions

Yajat Shamji
Jul 30, 2020

3 x + 4 x = 7 x 3x + 4x = 7x

2 y + 3 y = 5 y 2y + 3y = 5y

7 x + 5 y = 11 ( 3 ) = 33 7x + 5y = 11(3)= 33

Now setting y = 1 y = 1 , we find out which value of x x satisfies this equation:

7 ( 1 ) + 5 ( 1 ) = 12 33 7(1) + 5(1) = 12 \neq 33

7 ( 2 ) + 5 ( 1 ) = 19 33 7(2) + 5(1) = 19 \neq 33

7 ( 3 ) + 5 ( 1 ) = 26 33 7(3) + 5(1) = 26 \neq 33

7 ( 4 ) + 5 ( 1 ) = 33 7(4) + 5(1) = 33

Therefore, x = 4 x = 4

Since we are asked to give our answer in the form x y \overline{xy} , x y = 41 \overline{xy} = \fbox{41}

This is the exact same method I used!

Rikhin Kavuru - 10 months, 2 weeks ago

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Great! @Rikhin Kavuru

Yajat Shamji - 10 months, 2 weeks ago
Chew-Seong Cheong
Jul 29, 2020

For z = 3 z=3 , the equation reduces to 7 x + 5 y = 33 7x + 5y = 33 . Taking modulo of 5 5 on both sides, 2 x 3 (mod 5) x 4 2x \equiv 3 \text{ (mod 5)} \implies x \equiv 4 . Putting x = 4 x=4 in the equation, we have 28 + 5 y = 33 y = 1 28 + 5y = 33 \implies y = 1 . Therefore, x y = 41 \overline{xy} = \boxed {41} .

Wonderful idea!

Rikhin Kavuru - 10 months, 2 weeks ago
Rikhin Kavuru
Aug 1, 2020

First we simplify the equation to get 7 x x + 5 y y = 11(3); 33

Then, we should think of y y as 1 to start

Input = x x ; Output = x x + 7 (Per Each Equation)

7(1) + 5(1) = 12

7(2) + 5(1) = 19

7(3) + 5(1) = 26

7(4) + 5(1) = 33

This shows that the answer is 41 since x x is 4 and y y is 1

x = 33 5 y 7 x=\dfrac {33-5y}{7}

Only y = 1 , x = 4 y=1,x=4 are the positive integer values that satisfy this equation. So the answer is 41 \boxed {41} .

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