That's looking really easy

Algebra Level 1

Given if
2y + 3x = 22,
x + y = 9.
Find xy

Note: This question has been edited for clarity. Previously, it seemed to state 2 y + 3 x = 22 x + y = 9 2y+3x=22x+y=9 instead of 2 separate equations.

20 14 21 18

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5 solutions

Omkar Kulkarni
Jan 14, 2015

A faster method would be

2 y + 3 x = 2 ( x + y ) + x = 18 + x = 22 x = 4 , y = 5 2y+3x=2(x+y) + x = 18 + x = 22 \Rightarrow x=4 , y=5

It is a system of equations: 2 y + 3 x = 22 ( 1 ) 2y+3x=22\rightarrow (1) x + y = 9 ( 2 ) x+y=9\rightarrow (2) Substituting x = 9 y x=9-y into the first equation,we get; 2 y + 3 ( 9 y ) = 22 2 y 3 y + 27 = 22 y = 22 27 = 5 y = 5 2y+3(9-y)=22\rightarrow 2y-3y+27=22\rightarrow -y=22-27=-5\rightarrow y=\boxed{5} Substituting y = 5 y=5 into the second equation,we get; x + 5 = 9 x = 9 5 = 4 x+5=9\rightarrow x=9-5=\boxed{4} So x y = 4 × 5 = 20 xy=4\times5=\boxed{\boxed{\boxed{\boxed{\boxed{20}}}}}

Parth Lohomi
Nov 9, 2014

2 y + 3 x = 2 ( x + y ) + x = 2 ( 9 ) + x = 22 x = 4 2y+3x=2(x+y)+x=2(9)+x=22\implies x=4 , so y = 9 x = 5 y=9-x=5

\therefore x × y = 20 x\times y=\boxed{20}

Munem Shahriar
Jun 15, 2017

It was given that,

2 y + 3 x = 22 2y + 3x = 22 .............(1)

x + y = 9 x + y = 9 .....................(2)

Now , from equation (2)

x + y = 9 ⇒ x + y = 9

x = 9 y ⇒ x = 9 - y ...................(3)

Placing the value of x x in equation (1) to find y y

2 y + 3 ( 9 y ) = 22 ⇒ 2y + 3(9 - y) = 22

2 y y = 22 27 ⇒ 2y - y = 22 - 27

y = 5 ⇒ y = 5

Placing the value of y y in equation (3) to find x x

x = 9 5 ⇒ x = 9 - 5

x = 4 ⇒ x = 4

Multiplying x x and y y

= x × y = x \times y

4 × 5 = 20 4 \times 5 = 20

Arun Ar
Sep 2, 2014

2y + 3x = 22 ----------------------------------- I

x + y = 9------------------------------------------II

Equ I - 2 * Equ II

2y + 3x = 22 ------------------------------------III

-2x - 2 y = - 18 ---------------------------------IV

x = 4

y = 9 - 4

= 5

therefore x * y = 4 * 5 = 20

2y + 3x = 22 ----------------------------------- I

x + y = 9------------------------------------------II

Equ I - 2 * Equ II

2y + 3x = 22 ------------------------------------III

-2x - 2 y = - 18 ---------------------------------IV

x = 4

y = 9 - 4

= 5

therefore x * y = 4 * 5 = 20

Arun AR - 6 years, 9 months ago

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