Question

solve 125x^3 + 343 = 0

Answer 1

x = -1.4

subtract 343 on both sides and diide by 125 and take the cube root

Answer 2

it isnt 1.4 though

Answer 3

\[125x^3 + 343 = 0 \implies x^3=-\frac{343}{125} \implies x=-\frac{7}{5}\]

Answer 4

This is the only real solution.

Answer 5

yea i dont see how it can be anything else

Answer 6

mr. math, did you divide 125 by 343

Answer 7

@kanade: Actually it can. This equation has exactly three distinct roots over complex numbers.

Answer 8

@kamc23: I subtracted 343 from both sides and then divided by 125.

Answer 9

but when i divide 343 by 125 i get 2.744

Answer 10

if you take the cubed root of 2.744

is it 3 distinct roots due to the triangle created in the real and imaginary plane?

Answer 11

..?

Answer 12

Yes @kanade

Answer 13

i dont know how to take the cubed root of 2.744

Answer 14

Put 2.744^(1/3) in your calculator. :D

Answer 15

you could take the cube root of 343 and 125 individually and then divide to end up with 7/5 which you can get 1.4 then or you'd prob need to use a calculator

Answer 16

ughh i still dont get it