Question

solve by eliminating method 3x_4y=20;x+2y=5​

Answer 1

Answer:

1(3x-4y=20) = 3x - 4y = 20 --- 1.

2(x+2y=5​) = 2x + 4y = 10 --- 2.

Adding 1 and 2

==> 3x - 4y = 20

     2x + 4y = 10

                           

    5x        = 10

===> x = 10/5

       x = 5.

Put the value of x in 2.

3X5 - 4y = 20

15 - 4y = 20

-4y = 20/15

y = 4/3 X 1/-4

y = -1/3

Step-by-step explanation:

Hope it helps :)

Answer 2

Answer:

$\bigstar{\bold{The\:value\:of\:x\:is\:6}}$

$\bigstar{\bold{The\:value\:of\:y\:is\:\dfrac{-1}{2}}}$

Step-by-step explanation:

$\Large{\underline{\underline{\bf{Given:}}}}$

• 3x - 4y = 20
• x + 2 y = 5

$\Large{\underline{\underline{\bf{To\:Find:}}}}$

• The values of x and y by elimination method

$\Large{\underline{\underline{\bf{Solution:}}}}$

→ Multiply the second equation by 2, we get

  2x + 4y = 10

→ Solving the pair of equations by elimination method

   $3x- \cancel{4y} = 20$

   $2x+ \cancel{4y} = 10$

   $5x=30$

   $x=6$

→ Putting the value of x in the given equation

   x + 2y = 5

   6 + 2y = 5

   y = -1/2

$\boxed{\bold{The\:value\:of\:x\:is\:6}}$

$\boxed{\bold{The\:value\:of\:y\:is\:\dfrac{-1}{2} }}$

$\Large{\underline{\underline{\bf{Notes:}}}}$

A pair of linear equations can be solved by:

• Substitution method
• Elimination method
• Cross multiplication method