Question

Use the quadratic formula to find the zeros of the function. y = 16x2 + 40x + 25

A. {-1.25, 1.25}
B. {-1.25}
C. {-4, 5}
D. {-0.8}

Answer 1

Quadratic formula \[(-b \pm \sqrt{b^2-4ac})/2a\]
where a, b, c
\[ax^2+bx+c=0\]

Answer 2

Can you see why you need to use the quadratic formula now?

Answer 3

ok Go on the steps to solve it confuse me cuz there so long.

Answer 4

so in your case, 16=a, 40=b, 25=c. Plug them into the equation that Romero showed you.

Answer 5

You want to find the zeros of function Y right?
that means y=0
first do that
you get \[16x^2+40x+25=0\]

Answer 6

mkay wow go on that makes so much more sense than anything my teachers are saying does

Answer 7

like jessie said a =16 b=40 c=25
now plug them in the equation I gave you on top.

Answer 8

ok then i will then what do i do u dont have to give me the answer i just need the simple non confusing steps ur giving me.... ^^

Answer 9

The \[\pm\]means that you have to do one with + and one with - so it makes sense that you should get two values. You should be able to plug them in and whatever you get is the answer for X

Answer 10

ok ill plug them in for you but you work it out

Answer 11

ok i will i dont need the answer! lol just the steps!

Answer 12

a= 16 b=40 c=25
\[x= (-b \pm \sqrt{b^2-4ac})/2a\]

so if I plug them in I get

\[x= (-40 + \sqrt{40^2-4*16*25})/(2*16)\]
\[x= (-40 - \sqrt{40^2-4*16*25}) / (2*16) \]

Answer 13

so just do all the multiplication division etc and you should get your answers

Answer 14

OH!!!! Ok thank you thank you!! xD

Answer 15

I plugged the first numbers in and then i got 8.75 as my answer... but thats not on the options!

Answer 16

check your signs!!

Answer 17

i did!! thats why it took so long!

Answer 18

Ignore the rest, and look under the radical. Start 40^2, which is 1600. Then look at the rest of what is under the radical. Do -4x16x25. Do you get -1600? So the square root of 1600-1600 is 0.

Answer 19

Are we good to there?

Answer 20

yea i got that

Answer 21

but i didnt get the 1600 part for the first part i accidentally

Answer 22

put 4 because i squared the 40 then wasnt thinking and then i got the square root which was.. 40

Answer 23

so then would you do -40 + 32 ?

Answer 24

wait no im confused

Answer 25

Well remember, 2x16 is 32, but your not adding, you are dividing.

Answer 26

So You would have -40 plus the square root of all that junk that turned out to be zero.

Answer 27

-40/32 is -1.25

Answer 28

ohhhhh so u dont add?

Answer 29

wow ok thx i didnt even see that!!!

Answer 30

No. At the end, you set your equation OVER 2a. In other words, divide it by 2a.

Answer 31

ohhhhh ok?

Answer 32

http://www.regentsprep.org/Regents/math/algtrig/ATE3/quadsongs.htm

memorize the equation, if you're in Algerbra or Algerbra 2 you're gonna use it again!

Answer 33

algebra*

Answer 34

ok thx!!! ya im in Algebra IIthe only reason im bad is because of all the confusing steps!!!! :P but thx u helped me ALOT!!!

Answer 35

No problem.

Answer 36

What a pun

Answer 37

wait wait so i wrote the problem down like this:
x = (-b + -
Square root of…
B^2 – 4ac
/2a

Answer 38

and then were we doing b^2 - 4ac or somethin?

Answer 39

bc i didnt understand why i would divide by 2a again
which was 32

Answer 40

wait ok im confused UGH! i thought i got it!!!