Question

Can someone check this for me? (completing the square)

Answer 1

y = -2x^2 - 20x - 48

Answer 2

then i rewrote that into:

y = -2(x^2 - 20x ____) -48

-20/2 = -10 then square it and I got 100

y = -2(x^2 - 20x +100) -48

Answer 3

then I added 100 to both sides and I got:

y + 100= -2(x - 10)^2 -48
-100 -100
------------------------
y = -2(x - 10)^2 - 148

Answer 4

You subtracted 100 though ^

Answer 5

you add 48 to the other side and then also the 100 and the quadratic = 148

Answer 6

then you can factor the left side

Answer 7

can you show me that in steps? like from the beginning

Answer 8

you did it rite just set the equation = 0
then subtract 49 from both sides so
2x^2-20x=48

Answer 9

then complete the square and add the 100 to both sides

Answer 10

so it'd be 0 = -2(x^2 - 20x + 100) -48 ?

Answer 11

why do I need to factor that

Answer 12

Ok I got it thanks! and one more question

Answer 13

How would I solve:

x^2 - 38x + c

also by completing the square

Answer 14

c is a constant most likely just move it to the other side and complete the square

Answer 15

what is that going to give me?

Answer 16

x^2-38x=c

Answer 17

and what would be the next step

Answer 18

0 = (x2 - 38x ___) +c ?

Answer 19

square the -38 and do the same to both sides

Answer 20

(x^2-38x+__)=__-c

Answer 21

-38/2 = -19^2 = 361

Answer 22

yup

Answer 23

so that is on both sides

Answer 24

(x^2-38x+361)=361-c

Answer 25

okay so far i have:

(x^2 - 38x + 361) = 361 -c

Answer 26

right now you should be able to factor the quadratic
which is the point of completing the square

Answer 27

so like:

____ x___ = 361
____+___= -38

Answer 28

right
it will be the same number it is squared

Answer 29

-19

Answer 30

yup

Answer 31

(x-19)^2 = 361 - c?

Answer 32

and the first equation was x^2-10+25=49

Answer 33

right

Answer 34

what do I do now?

Answer 35

with the second you can't do anything it is most likely to show how you did the work

Answer 36

x-5=7

Answer 37

so just that ^

Answer 38

how would i write tht in intercept form

Answer 39

do you mean y=mx+b

Answer 40

no I also have to rewrite tht in intercept

Answer 41

the x intercept is +or-(7/5,0)

Answer 42

that is the y is 0