(1 +x)^(1/3) = 1 + (1/3)x- (1/9)x^2 + (5/81)x^3 - (10/243)x^4 + (22/729)x^5

Use this to get a quick numerical estimate of 70^(1/3).

I started by observing that 70 = 10*(1+6)

so... 70^(1/3) = (10*(1+6))^(1/3) = 10^(1/3) * (1+6)^(1/3)

I then used the binomial expansion of (1 +x)^(1/3), plugging inx= 6

I am getting an answer no where close to the true value of 70^(1/3)