Question

find coordinates of x/ y intercept and max or mini point on the grapg of these quad fuction. show answer by obtaining reasoing with sumbolic forms
help:
9a ) f(x)=x(7-x)
d) f(x)=-(x-3)(x+5)
g) f(x)=2(x-3)(x-8)

Answer 1

what's with reposting this?

Answer 2

my internet messed up

Answer 3

Try this one
f(x)=-(x-3)(x+5)

replace x with a 0
f(0)= -(0-3)(0+5)
can you do the arithmetic?

Answer 4

i dont remember how to

Answer 5

do the stuff in parens first (0-3) = ?

Answer 6

-3?

Answer 7

and (0+5) = ?

Answer 8

5

Answer 9

now -(-3)(5)
multiply it out the - sign out front is the same as -1
-1* -3 * 5

Answer 10

-15

Answer 11

a minus times a minus is a plus

Answer 12

so it would 15

Answer 13

so you found f(0) and that is the y-intercept.
now find the x - intercept. that is where
f(x)= 0
or, in this case,
-(x-3)(x+5) = 0

what x value makes this zero?

Answer 14

f=15 for the y itnecept?

Answer 15

y= 15 or f(0)= 15 is how you say it.

Answer 16

ok

Answer 17

so now how do i find x intecept

Answer 18

now find the x - intercept. that is where
f(x)= 0
or, in this case,
-(x-3)(x+5) = 0

what x value makes this zero?

Answer 19

3nd -5

Answer 20

so those are your x-intercepts

Answer 21

okay how would i write that

Answer 22

The parabola peaks at exactly between the two x-intercepts
so find the average of -5 and 3 to get where it peaks.

Answer 23

how do i do that

Answer 24

you could mark them down and start counting from -5 to 3 and then go to the half way point.

Answer 25

or you could add them together and divide by 2

Answer 26

i got -1

Answer 27

next, we need to know is this a max or a min?
Do you know? One way is put -1 in for x and figure out f(-1)

Answer 28

can u write it out

Answer 29

f(x)=-(x-3)(x+5)

replace the x with a -1

Answer 30

ok how to solve

Answer 31

Here is a picture.