Question

Solve: 125x^3 + 343=0
Find all Complex Roots.

Answer 1

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Answer 2

this is the sum of 2 cubics

(5x)^3 and (7)^3

then it can be factorised to

(5x + 7)(25x^2 - 35x + 49)

the quadratic needs to be solved by general quadratic formula

\[x = (35 \pm \sqrt{245})/10\]

then the solutions are

\[x = (35 \pm 7\sqrt{5})/10\] and x = - 7/5

Answer 3

so could that be -7/5, and 35 plus/minus 35i sqrt 3 over 50

Answer 4

yep... there are 3 roots