What is 7x cubed plus 2 x equals 60?

Answer 1

7x3 + 2x = 60

7x3 + 2x - 60 = 0

7x3 - 28 x + 30x - 60 = 0

7x(x2 - 4) + 30(x - 2) = 0

7x(x + 2)(x - 2) + 30(x - 2) = 0

(x - 2)[7x(x + 2) + 30] = 0

(x - 2)(7x2 + 14x + 30) = 0

x - 2 = 0 or 7x2 + 14x + 30 = 0

x = 2 or

x = {-14 +&- square root of [142 - 4(7)(30)]}/(2)(7)

x = -14/14 +&- (square root of -644)]/14

x = -1 +&- 2i(square root of 161)/14

x = -1 +&- (square root of 161)i/7