Question

can someone please solve and explain the following quadratic equation? 4x^3 - 3x^3 + 60x = 0, x=?

Answer 1

This is not a quadratic equation!!!

Answer 2

Its cubic

Answer 3

check if u hv typed it properly

Answer 4

I did type it properly but it says in my book it is a quadratic equation;/

Answer 5

book is lying

Answer 6

@Harkirat what was with all the exclamation points?

Answer 7

There can be typographical errors in a book.....

Answer 8

Well, assuming that there was a typo, and the equation is as follow
\[x ^{3} - 3x^{2} + 60x = 0 \] we can do the following:
\[x(x^{2} - 3x + 60) = 0\]
\[x=0\] is one answer , the other ones, just solve \[x^{2} - 3x + 60 = 0\]

Answer 9

@Dijah
Just expressing my surprise .. :))

Answer 10

well if you simplify it, it becomes x(x^2 +60) = 0, and then you would simply be solving a qudratic

Answer 11

@poring
she has not confirmed the typo....

Answer 12

is there anyway to solve this problem though? I couldn't figure it out...

Answer 13

@Lydia

Is the second term -3x^3 or -3x^2 ??

Answer 14

4x^3 - 3x^3 +60x = 0 simplifies to x^3 +60x = 0. Then factor out an x and you have x(x^2+60) = 0. Then one solution of x will be 0, and you will get the other two solutions by applying the quadratic formula to x^2 +60 = 0.

Answer 15

@Hakirat it's -3x^3

Answer 16

if it helps i have the answer, i just don't understand how they got it....

Answer 17

Assuming there is no typo:\[4x ^{3}-3x ^{3}+60x=0\]
\[x ^{3}+60x=0\]
\[x(x ^{2}+60)=0\]
x=0
\[x ^{2}+60=0\]
\[x=\sqrt{-60}=\sqrt{4}\sqrt{-15}=2\sqrt{15}i\]

Answer 18

thank you @radar, but the book must have had a typo...because the answer in the book says (0,5,3), and there's no possible way to get that unless the book actually typed the equation wrong.

Answer 19

I really think they meant for the second term to be some x^2 rather than the -3x^3.

Answer 20

i think you're right, because all the other equations in the book had the second x raised to the 2nd power except this one...plus the answer doesn't match up. but thanks for your guys' help:)

Answer 21

what is the question?

Answer 22

if its an equation that i no how to do. I will help

Answer 23

you are welcome, one other thing, I don't know how they have been teaching, but the square root of 4 is actually +/1 2 so the answer might also be
\[\pm 2\sqrt{15}i\]

Answer 24

no its a simple 2

Answer 25

thank you radar!! :D

Answer 26

\[*** \pm 2\]

Answer 27

kool

Answer 28

It would have three roots: 0, and\[2\sqrt{15}i, and -2\sqrt{15}i\]

Answer 29

@radar is right

Answer 30

I worked backwards from the three given roots and landed up with the equation
x^3 - 8x^2 + 15x = 0
multiplying throughout by 4, we get
4x^3 - 32x^2 + 60x = 0

Anybody for confirming this ????

Answer 31

Was this the roots of 0, 5, and 3?

Answer 32

yes, that is what she mentioned......I think.......

Answer 33

x=0 for sure lol, I think that was what was wanted to be solved, but it got typoed!

Answer 34

@harikat, the 5 works also

Answer 35

Confirmed

Answer 36

so we find the right equation for these values is
4x^3 - 32x^2 + 60x = 0

So Lydia, I suggest you modify the equation to what i hv written and solve it
you will get the roots given as answer.......

Answer 37

@Harkirat your picture reminds me of the lion king

Answer 38

Thanks for liking it.
Actually I am a Sikh from the Punjab state of India. My community is lion-hearted by nature and my surname also means "lion". So I found this nice picture and used it....

Answer 39

I am thankful to all who gave me medals o((:-})>

Answer 40

it was me ;)

Answer 41

thank u very much... ☺

Answer 42

thank you guys for helping me with this, it really saved me some worrying:) good teamwork!