Can someone explain to me how to do this ?

Step-by-step explanation:

y=-(x³)

take the points x=-2,-1,0,1,2

y=8,1,0,-1,-8

plot the points (-2,8),(-1,1),(0,0),(1,-1),(2,-8)

2.

y=-x²

take the points x= -2,-1,0,1,2

y=-4,-1,0,-1,-4

plot the points (-2,-4),(-1,-1),(0,0),(1,-1),(2,-4)

you can't solve x because it is 2 linear equation and you only have one equation