Question

M=5N³+70N²,求N

Answer 1

N = (3 sqrt(3) sqrt(27 M^2-54880 M)+27 M-27440)^(1/3)/(3 10^(1/3))+(196 10^(1/3))/(3 (3 sqrt(3) sqrt(27 M^2-54880 M)+27 M-27440)^(1/3))-14/3

N = -((1-i sqrt(3)) (3 sqrt(3) sqrt(27 M^2-54880 M)+27 M-27440)^(1/3))/(6 10^(1/3))-(98 10^(1/3) (1+i sqrt(3)))/(3 (3 sqrt(3) sqrt(27 M^2-54880 M)+27 M-27440)^(1/3))-14/3

N = -((1+i sqrt(3)) (3 sqrt(3) sqrt(27 M^2-54880 M)+27 M-27440)^(1/3))/(6 10^(1/3))-(98 10^(1/3) (1-i sqrt(3)))/(3 (3 sqrt(3) sqrt(27 M^2-54880 M)+27 M-27440)^(1/3))-14/3