Question

systems of equations help!

Answer 1

@CGGURUMANJUNATH can you help?

Answer 2

@welshfella can you help at all?

Answer 3

I think i am supposed to use elimination for this one.

Answer 4

yes these are not too hard
first subtract them to eliminate y
then you'll have a quadratic to solve

Answer 5

okay do i have to expand the bottom equation first?

Answer 6

or i guess i would expand both of them

Answer 7

no
the x^2 will cancel so you'll only have a linear

Answer 8

okay so when i eliminate y i get (x-1)^2=9 and (x-2)^2=4

Answer 9

you get (x - 1)^2 - (x - 2)^2 = 5

Answer 10

oh i combine them, my bad i forgot.

Answer 11

you'll find it easy to solve for x

Answer 12

shouldnt it be 12 instead of 5?

Answer 13

ah nevermind, ignore me. you subtract them.

Answer 14

so to solve for x i could end up with 2x^2-6x=1

Answer 15

then do i factor it our and take those 2 answers and plug it back in for y in an original equation?

Answer 16

no - the x^2 is eliminated
x^2 - 2x + 1 - (x^2 - 4x + 4) = 5

Answer 17

hmm wait what

Answer 18

after you have (x-1)^2-(x-2)^2=5 what do you do? cause i expanded them and was simplifying

Answer 19

yes expand - but watch the signs

Answer 20

put the second expansion in parentheses - then you are less likely to make mistakes

Answer 21

i did..im not sure where i went wrong

Answer 22

but you see how the x^2 disappears/

Answer 23

hmm no i have a positive x^2 and another positive x^2

Answer 24

because i distributed the negative to (x-2)^2

Answer 25

was i not supposed to do that?

Answer 26

a negative outside the parentheses is like a -1 - you need to multiply contents of the bracket by -1

Answer 27

do the expansion first then distribute the negative

Answer 28

okay so x^2-2x+1 and x^2-4x-4

Answer 29

right

Answer 30

okay but should you distribute the negative first?

Answer 31

x^2 - 2x + 1 - (x^2 - 4x + 4)
now distribute the negative
= x^2 - 2x + 1 - x^2 + 4x - 4

Answer 32

okay yeah so then after that you simplify it down and get 2x-4=5?

Answer 33

2x - 3 = 5

Answer 34

giving x = 4

Answer 35

oh i forgot about the one. thanks. so then i take x and plug it back into the original equation to find y?

Answer 36

yes

Answer 37

plug it into both equations as a double check

Answer 38

okay it works! thanks!

Answer 39

yw