Question

Если 4x^2-9 = 11, каково значение x^3 + 2x

Answer 1

4x ^ 2 = 20 => x = +/- sqrt (5);
x ^ 3 + 2x = sqrt (5) * (5 + 2) = +/- 7 * sqrt (5)

Answer 2

4x ^ 2-9 = 11
4x ^ 2 = 20
х ^ 2 = 5x = +/- sqrt (5)

х ^ 3 + 2х
если x = sqrt (5)
5 sqrt (5) + 2 sqrt (5) = 7 sqrt (5)
если x = -sqrt (5)
-5 sqrt (5) + -2 sqrt (5) = -7 sqrt (5)
= +/- 7 sqrt (5)