Question

use the subsitution to solve the system of linear equations

3x-y=8
7x-2y=21

Answer 1

ok do you understand the term "Substitution?"

Answer 2

Yes

Answer 3

ok first thing rearrange the first equation to the general linear form y=mx + c
1) 3x - y = 8
3x -8 = y
y=3x-8

Now we want to substitute y=3x-8 into the second equation given which is 7x-2y=21
7x - 2y = 21
7x - 2(3x-8) = 21
7x -6x + 16 = 21
x + 16 = 21
x = 21-16
x = .......... (I'm sure u can do this)

Answer 4

5

Answer 5

yes that is correct.

Answer 6

but do u understand the concept?

Answer 7

Thankk Youu !

Answer 8

Yess Andd Will 5 Be Myy Ordered Pair ?

Answer 9

nope, that is just your x-value for your ordered pair.

Answer 10

there is one more step, just substitute x=5 into either of the original equation to find your y-value.
currently you have (5,?)
we need to find the ? which is your y-value of the ordered pair.

Answer 11

Okai And How Do I DO That

Answer 12

simply substitute x=5 into either of the original equations which are 3x-y=8 or 7x-2y=21

Answer 13

Okaii Im Stuckk Can You Please Help Me Out

Answer 14

ok, we figured x=5 already and we choose one of the original equations, lets choose 3x-y=8

remember substitute means "replace" so we replace x=5 into that equation we choose.
3x-y=8
3(5) - y = 8
15 - y = 8
y = ....... (you can do this)

Answer 15

7 ?

Answer 16

yes that is correct, now tell me the final ordered pair which is your solution/answer.

Answer 17

(4,7)

Answer 18

no.... (5,7)

Answer 19

remember we found x=5 at first, how can it become a 4?

Answer 20

Oh Yes Im So Sorry i Had Forgot AbOut This ! Its Confusing !

Answer 21

No Can You Please Help Me With This One To
use the method of substitution to solve linear equations 7a=3-b and 7a=7-b

Answer 22

use the eliminatiuon method to solve the system of equations
a+8b=1
a+4b=-3

Answer 23

http://www.mathsteacher.com.au/year10/ch04_simultaneous/03_elimination_method/elim.htm

Answer 24

And What Will The A Be?

Answer 25

u have to solve it and tell me.

Answer 26

Will I Use The A As A 1 ?