Question

Which of the following is a zero for the function f(x) = (x – 15)(x + 1)(x – 10)?

x = –15

x = –10

x = 1

x = 15

Answer 1

Can you help me?? @Meepi

Answer 2

what do we know about multiplication, that gets us a zero?

Answer 3

6, times what ... equals zero?

3, times what .... equals zero?

198726735544783836734, times what .... equals zero?

Answer 4

6 times 0 = zero

Answer 5

I dont get what youre trying to say by that @amistre64

Answer 6

its a property, that is useful to us here.

you have 3 numbers, multiplied together.

(x – 15), (x + 1), and (x – 10)

to determine what value of x, creates a zero.... we only need to define what values of x will produce a zero in any of the numbers given

Answer 7

(x – 15) = 0, what is x?

(x + 1) = 0, what is x?

(x – 10) = 0, what is x?

Answer 8

x always zero??? @amistre64

Answer 9

lets see, if x = 0 then we get:

(0 – 15) = -15, not it

(0 + 1) = 1 , not it

(0 – 10) = -10 , not it

when x=0, we do not produce a number that is zero.

Answer 10

but it's asking for the function f(x) = (x – 15)(x + 1)(x – 10)?

Sorry im confused... @amistre64

Answer 11

do you see that when "x" is equal to a certain value, that we get 3 numbers that multiply together?

Answer 12

So its not zero, would it be x= 1
since the number would than equal its self

Answer 13

f(x) = (x – 15)(x + 1)(x – 10)

if x = 0 then we get:

f(0) = (0 – 15)(0 + 1)(0 – 10)

f(0) = (–15)(1)(–10) = 150

since 150 is not equal to zero, then x=0 is does not create a zero.

Answer 14

lets try x=1

f(1) = (1 – 15)(1 + 1)(1 – 10)
not0 not0 not0


f(1) = (–14)(2)(–9) = not0

recall the property i hinted at. to multiply numbers together and get zero, one or more of the numbers HAVE to be zero.

Answer 15

f(x) = (x – 15)(x + 1)(x – 10)

we can take each number they give us, and equal it to zero

(x – 15) = 0, what would x have to be for this to be zero?

(x + 1) = 0, what would x have to be for this to be zero?

(x – 10) = 0, what would x have to be for this to be zero?

Answer 16

15
-1
10

I'm still confused lol

Answer 17

you are absolutely correct tho :)

Answer 18

f(15) = (15 – 15)(15 + 1)(15 – 10)

f(15) = 0 (15 + 1) (15 – 10) = 0

and it works for the other zeros you found as well

Answer 19

So what would the answer be?

Answer 20

so given our set of zeros:

x = {15,-1,10}

which of the options will be correct?

x = –15

x = –10

x = 1

x = 15

Answer 21

15???

Answer 22

correct :)

Answer 23

Thank you!