Question

cansomeone show me how to solve this? Use the quadratic formula to find the zeros of the function. y = 16x2 + 40x + 25
{-1.25, 1.25}
{-1.25}
{-4, 5}
{-0.8

Answer 1

do you recall the setup of the quadratic formula?

Answer 2

\[\frac{ -b \pm \sqrt{b ^{2}-4ac} }{ 2a }\]

Answer 3

good, and the general form of a quadratic is:

\[ax^2 + bx + c\]
pull the numbers from the problem that relate to the abc parts and what do you get worked out?

Answer 4

a=16 b=40 and 25=c

Answer 5

good, i notice that there are no - signs to worry about so that looks good so far

Answer 6

what do i do next?

Answer 7

plug in those numbers into their abc parts in the formula, the rest is just math for maths sake

Answer 8

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

Answer 9

\[\frac{ -40\pm \sqrt{40^{2}-4(16)(25)} }{ 2(16) }\] is that right?

Answer 10

looks good to me :)

Answer 11

ok then i get 40 pm 16-96/32?

Answer 12

but i would end up eith a negative number....

Answer 13

\[\frac{ -40\pm \sqrt{40^{2}-4(16)(25)} }{ 2(16) }\]
\[\frac{ -40\pm \sqrt{4^2(10)^2-4(4^2)(25)} }{ 2(16) }\]
\[\frac{ -40\pm 4\sqrt{10^2-4(25)} }{ 2(16) }\]
\[\frac{ -40\pm 4\sqrt{25(4)-4(25)} }{ 2(16) }\]
\[\frac{ -40}{ 2(16) }\]
\[\frac{ -40}{ 2(4.4) }\]
\[\frac{ -10}{ 2(4) }\]
\[\frac{ -5}{ 4 }\]

Answer 14

you lost me at the second one you did how did you get all the the ^2?

Answer 15

40^2 = (4*10)^2 = 4*10 * 4*10 = 4^2 * 10^2

but you dont have to do exactly what i did

Answer 16

uuuuh.....im sorry you lost me all i know is im suppose to square 40 is that what you were doin?

Answer 17

@amistre64 ?

Answer 18

i was doing some manipulations so that i didnt have to worry about computing large numbers and such; i simplified it down to where i recognized the sqrt part goes to zero.

Answer 19

but 40^2 - 4(16)(25) = 0

Answer 20

ui havent learned taht i think im suppose to just use the big numbers

Answer 21

then math it out for maths sake, youll get big numbers that finally reduce and simplify

Answer 22

i tried but i keep getting teh wrong number when i have 40^2-4(16)(5) i get 0 right? i get 1,600 -1,600 and i cant square thaty

Answer 23

what does 1600 - 1600 equal?

Answer 24

0 -_- i cant square 0

Answer 25

sure you can, 0*0 = 0

Answer 26

oooooh......

Answer 27

so -40 pm 0/32?

Answer 28

\[\frac{ -40\pm \sqrt{40^{2}-4(16)(25)} }{ 2(16) }\]
\[\frac{ -40\pm \sqrt{1600-1600} }{ 2(16) }\]
\[\frac{ -40\pm \sqrt{0} }{ 2(16) }\]
\[\frac{ -40\pm 0 }{ 2(16) }\]
\[\frac{ -40}{ 2(16) }\]

Answer 29

yes /32 is fine as well

Answer 30

THANK YOU SO MUCH!!!!!

Answer 31

youre welcome

Answer 32

so its -40/32?

Answer 33

yes, which a calculator should be able to put into decimals for you

Answer 34

-1.25?

Answer 35

correct

Answer 36

thank you!