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

Dear reader, solve this question and send it to me in the comment section. Get it correctly and win a prize. If you’re in Nigeria, you will win airtime. If you’re outside Nigeria, you will win Free Online Tutorial for some period.(Limited to the first three persons)

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## Published by ginnyent

CHG Ofokansi is an author, a medical laboratory scientist and a teacher who has several books for children and adults.
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