Linear Equation in 2 variables

Algebra Level 2

x y \frac { x }{ y } Is a fraction in which Numerator of the fraction is 1 more than the twice of the denominator. If 2 is added to numerator and 3 is added in denominator then fraction become 3 2 \frac { 3 }{ 2 } Find the fraction and enter the product of x and y


The answer is 21.

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3 solutions

Ankit Vijay
May 30, 2014

L e t x y b e t h e f r a c t i o n 2 y + 1 = x x 2 y = 1 . . . ( i ) x + 2 y + 3 = 3 2 2 x 3 y = 5 . . . ( i i ) M u l t i p l y i n g ( i ) b y 2 ( e l i m i n a t i o n m e t h o d ) a n d t h e n s u b t r a c t i n g i t b y ( i i ) 2 x 4 y = 2 2 x 3 y = 5 ( c h a n g i n g o f s i g n s ) 0 y = 3 y = 3 S u b s t i t u t i n g t h e v a l u e o f y i n ( i i ) 2 x 9 = 5 2 x = 14 x = 7 H e n c e t h e f r a c t i o n i s 7 3 A n d t h e p r o d u c t o f x a n d y i s 21 Let\quad \frac { x }{ y } \quad be\quad the\quad fraction\quad \\ 2y+1=x\quad \quad \Rightarrow \quad x-2y=1\quad ...(i)\\ \frac { x+2 }{ y+3 } =\frac { 3 }{ 2 } \Rightarrow 2x-3y=5\quad ...(ii)\\ \\ Multiplying\quad (i)\quad by\quad 2\quad (elimination\quad method)\\ and\quad then\quad subtracting\quad it\quad by\quad (ii)\\ 2x\quad -4y\quad =\quad 2\\ 2x\quad -3y\quad =\quad 5\\ \ominus \quad \oplus \quad \quad \quad \quad \ominus \quad \quad \quad \quad (changing\quad of\quad signs)\\ 0\quad -y\quad \quad \quad =-3\\ \\ y=3\\ \\ Substituting\quad the\quad value\quad of\quad y\quad in\quad (ii)\\ 2x-9=5\\ 2x=14\\ x=7\\ \\ Hence\quad the\quad fraction\quad is\quad \frac { 7 }{ 3 } \\ And\quad the\quad product\quad of\quad x\quad and\quad y\quad is\quad 21

These problems are good for practising.... :)

Krishna Ar - 7 years ago
Filly Mare
Jun 10, 2014

x = 2 y + 1 x + 2 y + 3 = 2 y + 1 + 2 y + 3 = 2 3 x=2y+1 \Rightarrow \frac{x+2}{y+3}=\frac{2y+1+2}{y+3}=\frac{2}{3} Cross multiplying gives: 3 ( y + 3 ) = 2 ( 2 y + 3 ) 3 y + 9 = 4 y + 6 y = 3 3(y+3)=2(2y+3) \Rightarrow3y+9=4y+6 \Rightarrow y=3 Substitute y into x = 2 y + 1 x=2y+1 to give x = 7 x=7 7 × 3 = 21 \rightarrow 7 \times 3 = \boxed{21}

Mehul Arora
Dec 18, 2014

This can be solved as a single variable equation!!

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