Область определения:
а) y = √(x + 4)
x + 4 ≥ 0
x ≥ - 4
D(y) = [-4 ; + ≈)
в) y = (2x + 1)^(1/3)
D(y) = ( - ≈; + ≈) или D(y) = R
д) y = 4/(2x - 5)^(1/4)
2x - 5 > 0
2x > 5
x > 2,5
D(y) = (2,5 ; + ≈)
См. приложение
++++++++++++++++++++++++++++++++++
2а-10b/(3a^2-75b^2)=
=2(a-5b)/(3(a^2-(5d)^2))
=2(a-5b)/(3(a-5b)(a+5b))
=2/(3(a+5b))=2/(3a+15b)
(81-b²)-(27-b³) = (81-1)-(27+1)=80-28=52