Question

In simultaneous equation, use the method of elimination solve for x and y

4x-3y=11
2x+5y=25

Answer 1

x=5, y=3

Explanation:

4x=11+3y. ..equation 1

2x=25-5y. ...equation 2

now, let eq' 1 be multiplied by 1 and eq' 2 be multiplied by 2

4*1x=11*1+3*1y

4x=11+3y

2*2x=25*2-5*2y

4x=50 -10y

now , subtract eq' 2 from eq' 1

4x=11+3y

4x=50 -10y

- - +

0 =-39+13y

39=13y

y=3

now substitute the value of y in equation 2

2x=25-5y

2x=25-5*3

2x =25-15

2x=10

x=5

Answer 2

4x - 3y = 11

2x + 5y = 25

We'll double the second equation so it has the same x term as the first equation:

4x + 10y = 50

Then let's subtract this from the first equation"

-13 y = -39

Divide both sides by -13:

y = 3

Now let's substitute in one of the equations to get x:

2x = 25 - 5y = 25 - 5(3) = 10

x = 5

Answer: x=5, y=3

Check:

4(5) - 3(3) = 20 - 9 = 11, good

2(5) + 5(3) = 10 + 15 = 25, good