Question

Simultaneous equation 3x+y=8 , x-3y=11

Answer 1

X=18.5,Y=-2.5

Explanation:

Using substitution method

3x+y=8.........(equation 1)

x-3y=11...…....(equation 2)

Making x in equation 2 has subject of the formula

x=11+3y

Substitute x in equation one

3(11+3y)+y=8

33+10y=8

10y=8-33

10y=-25

y=-25/10

y=-2.5

Substitute y in equation 2

x-3(-2.5)=11

X-7.5=11

x=11+7.5

x=18.5

Answer 2

Answer: x = 3.5 and y = -2.5

Step-by-step explanation: The pair of simultaneous equations are given as

3x + y = 8 ———(1)

x - 3y = 11 ———(2)

From equation (2) make x the subject of the equation

x = 11 + 3y

Substitute for the value of x into equation (1)

3(11 + 3y) + y = 8

33 + 9y + y = 8

We collect like terms and we now have

33 - 8 = -10y

25 = -10y

Divide both sides of the equation by -10

-2.5 = y

Having solved for the value of y, we now substitute for y into equation (2)

x - 3y = 11

x - 3(-2.5) = 11

x + 7.5 = 11

x = 11 - 7.5

x = 3.5

Therefore x = 3.5 and y = -2.5