Verified answer

(x+3)^2 * (1+x)^7/3 - (1+x)^4/3 * (x+3)^3 + (x+3)^4 * (1+x)^1/3

(x + 3)²*(1+x)^(7/3) = (x + 3)²*(x + 1)²*³√(x + 1)

(x + 1)^(4/3)*(x + 3)³ = (x + 3)²(x + 3)*(x + 1)*³√(x + 1)

(x + 3)^4*(x + 1)^(1/3) = (x + 3)²*(x + 3)²*³√(x + 1)

³√(x + 1)*(x + 3)² * ( (x + 1)² - (x + 3)*(x + 1) + (x + 3)² ) =

³√(x + 1)*(x + 3)² *( x² + 2x + 1 - x² - 4x - 3 + x² + 6x + 9) =

³√(x + 1)*(x + 3)² * (x² + 4x + 7)

pronto