Question

solve by substitution
2.5x-3y=-3
3.25x-y=-14

Answer 1

rearrange the first equation in terms of y
2.5x - 3y=-3
2.5x + 3 = 3y
y= 2.5/3x + 3/3
y=2.5/3x + 1

now substitute that as y into the second equation 3.25x-y=-14
try it yourself.

Answer 2

\[2.5x-3y=-3\]
Use the second equation to make y the subject. Since you just need to move values to the LHS and RHS. You don't need to do much about it.
\[y=3.25x+14\]
Now for every y you see in the first equation write (3.25x+14).
\[2.5x-3(3.25x+14)=-3\]

Answer 3

\[2.5x-3(3.25x)-3(14)=-3\]
\[2.5x-10.75x-42=-3\]

Answer 4

Collect like terms and solve for x.

Answer 5

hold up im just working it out!

Answer 6

wait wouldnt it be 9.75

Answer 7

instead of 10.75 wouldnt be 9.75x

Answer 8

Oh yeah. Good spotting mate. Excellent work. You should always look at everything I wrote or you might of copied wrong working out. ;)

Answer 9

That's good work ethic. Always do that and you will succeed in math.

Answer 10

So.
][2.5x-9.75x-42=-3\]

Answer 11

\[2.5x-9.75x-42=-3\]

Answer 12

haha thank you! would the answer be x=-.1858

Answer 13

Nope, incorrect. Start by collecting like terms.

Answer 14

Show me when you collected your like terms.

Answer 15

okay so i collected 2.5x-9.75 and i got -7.25 correct?

Answer 16

okay so i collected 2.5x-9.75xand i got -7.25x correct?

Answer 17

Okay. I'm a bit of a hater towards negative signs on x's. So I would move the -7.25x to the RHS so that you eliminate that minus sign.

Answer 18

Move the constants to the LHS.

Answer 19

what do you mean?

Answer 20

RHS=Right Hand Side

Answer 21

\[-7.25x-42=-3\]

Answer 22

Move the term
\[-7.25x\] to the RHS (Right Hand Side of the equal sign.)

Answer 23

So
\[-42=-3+7.25x\]

Answer 24

Move the -3 to the LHS(Left Hand Side of the equal sign). Could you do that for me?

Answer 25

yes so the answer is -5.37

Answer 26

Correct buy you didn't round up properly.

Answer 27

but*

Answer 28

so -5.4

Answer 29

\[-5.379\neq -5.37 \]

Answer 30

I mean you didn't round up to the nearest hundredth properly.

Answer 31

\[-5.379=-5.38\]

Answer 32

5.4 is also correct. But it depends on whether your question asks you to round up to the nearest decimal place or the nearest 2 decimal places.

Answer 33

it doesnt say that so would it just be 5.4

Answer 34

If your questions does not ask you to round up. Answer it as a fraction.

Answer 35

it doesnt say round or anything

Answer 36

question*

Answer 37

and i still have to solve for y right?

Answer 38

Do not round up if they don't ask you to. Always put it to the best possible answer which is a fraction. Fractions is much more accurate than the rounded up decimal.

Answer 39

Yes. That's why never round up when you need to use that number to find another number.

Answer 40

So substitute the fraction into one of the two equations given to you from your question (preferrably the second equation) to find the y-value.

Answer 41

5.4= 27/5 as a fraction? so i would sub that in for x in the seconf equation

Answer 42

No. 27/5 is still 5.4. That's still the rounded up fraction.

Answer 43

And it's meant to be a negative fraction not a positive.

Answer 44

\[-\frac{156}{29}\]