Let’s Solve the Exercise…

Published on ginnyent on 4th April, 2019
Let’s Solve the Exercise Given Last Tuesday on Simultaneous Equation
The first question:
3x + 7y = 26
2x +4y = 16

Solution
Let the two equations be equation 1 and 2 respectively.
3x + 7y = 26———1
2x +4y = 16———-2

We are going to make x or y the subject of either of the equations
If we make x the subject of formular in equation 1, we would have:
x= 16- 4y ———- 3
2
We will now substitute for x in equation 1, we would have:
3(16- 4y) + 7y = 26
2
Opening the bracket, we would have:
48 -12y + 7y = 26
2
To eliminate the 2 under 48-12y, we have to multiply through by 2.
2(48-12y) + 2(7y) = 2(26)
2
So we have:
48 -12y + 14y = 52 (Do you understand?)
Collecting like terms, we have:
-12y + 14y = 52 – 48
2y = 4
y= 4/2
y = 2
Now, we are going to find x. We can use any of the three equations to find x.
If we use equation 3.
X = 16- 4y
2
x = 16 – 4(2)
2
= 16-8
2
= 8/2
x = 4

Question 2.
x + 3y = 8
5x + 7y = 24

Solution
x + 3y = 8 ———–1
5x + 7y = 24 ——-2
From Equ. 1,
x = 8 – 3y ———–3
We will now substitute for x in equ. 2, we will have:
5(8-3y) + 7y = 24
Opening the bracket we will have:
40 – 15y + 7y = 24
Collecting like terms, we will have
-15y + 7y = 24 – 40, so we have:
-8y = – 16
y = -16/-8
y = 2 (understood?)

Now, we will solve for x. Using equ. 3,
X = 8 – 3y
= 8 – 3(2)
= 8 – 6
x = 2

Question 3.
y-5x = 12
y +4x =30