Question

MEDAL AND FAN

For the following system, use the second equation to make a substitution for y in the first equation.

3 x + y = 2
y + 4 = 3 x

ANSWERS:
3 x + 3 x - 4 = 2
3 x + 3 - 4 x = 2
3 x + 3 x + 4 = 2

Answer 1

\(\large\color{blue}{ \rm 3 x + y = 2 }\)
\(\large\color{blue}{ \rm y + 4 = 3 x }\)


\(\large\color{blue}{ \rm 3 x + y = 2 }\)
\(\large\color{blue}{ \rm 3x-y = 4 }\)

Answer 2

?

Answer 3

i dont understand

Answer 4

y + 4 = 3 x

since 4 is ADDED to 'y'
SUBTRACT 4 from both sides to isolate 'y'
what u get ?

Answer 5

May I ask what type of equation is this called? I remember doing this ages ago...I want to learn this again.

Answer 6

im getting so confused by this subject. its hard for me to grasp this

Answer 7

3 x + y = 2
y + 4 = 3 x
is a system of linear equations
with 2 linear equation.

to solve them simultaneously, (to find x and y)
there are several methods,
i) elimination,
ii) substitution
and some others...

what solmon suggested is elimination method

what question expects and i suggested is substitution method

Answer 8

You're not alone spasekat, hahaha. I'm confused here too. Thanks hartnn! :)

Answer 9

y + 4 = 3 x

subtract 4 from both sides
can you do that ?

Answer 10

do i subtract 4 from x?

Answer 11

right side = 3x
if you subtract 4,
it'll be
3x-4

they won't combine , because they are NOT like terms

Answer 12

what about left side ?

Answer 13

y - 4?

Answer 14

or y + (-4)

Answer 15

it was y+4

you subtract 4

y+4-4
what does that equal ?

Answer 16

0

Answer 17

y + 4-4 = 3x - 4

Answer 18

yes
4-4 =0
and y+0 = y

so, we have
\(\Large y = 3x-4\)
clear ?

Answer 19

yes

Answer 20

now look at 1st equation

3x+y = 2

but we already got y = 3x-4

so replace 'y' in first equation with '3x-4'
what do u get ?

Answer 21

3x + 3x - 4 = 2

Answer 22

good!
thats your first option :)
any doubts ?

Answer 23

no :D

Answer 24

that was really helpful! i am a fan and medal now for you

Answer 25

thanks :D