Question

3x + 5y = 4 2x + 3y = 4 solve in elimination

Answer 1

y=-4, x=8

Explanation:

1)3x+5y=4

2)2x+3y=4

Make 1 and 2 have the same co-efficient of x or y (i chose x as it is easier to get to 6 then 15)

Label the 2 new equations as 3 and 4

3)6x+10y=8

4)6x+9y=12

Now we can take away to give

y=-4

Now we substitute this into 1 or 2

I chose 2:

2x+3(-4)=4

2x=4+12

2x=16

x=8

Answer 2

x = 8

y = -4

Explanation:

Multiply the first equation by 2:

⇒ 3x + 5y = 4 ⇒ 6x + 10y = 8

(we will call this equation 3)

Multiply the second equation by 3:

⇒ 2x + 3y = 4 ⇒ 6x + 9y = 12

(we will call this equation 4)

Subtract equation 3 from equation 4 to eliminate the x variable:

6x + 9y = 12

- 6x + 10y = 8

-y = 4

Therefore, y = -4

Substitute y = -4 into one of the equations and solve for x:

3x + (5 x -4) = 4

⇒ 3x - 20 = 4

⇒ 3x = 24

⇒ x = 8