Kelly is trying to work out the two values of w for which 3w - w^3 = 2 Her values are 1 and -1 Are her values correct? You must show your working.

Firstly substitute her first value into the equation so w=1 giving (3 x 1) - (1)^3 = 3 - 1= 2 so her first value for w is correct Next substitute the second value into the equation so w= -1 giving (3 x -1) - (-1)^3 = -3 - -1 (because when you cube a negative number it remains negative) this then = -3 + 1 = -2 so her second value is incorrect