choose the expression that represents a cubic expression.
−7x + 14
7x2 − 5x + 6
8x3 − 7x2 − 6x + 5
9x4 + 8x3 − 6x2 − 2x + 11

Answer: 8x^3-7x^2-6x+5
a cubic expression is one that the highest exponent or power is 3 or cubed. the first two the highest exponent is only x or x^2 so they aren’t cubic. the first one is a linear expression and the second one is a quadratic expression. the third choice is correct as its highest power is x^3 so this is a cubic expression. and the last choice isn’t correct as it is a quartic expression or a polynomial of degree 4. i hope this explanation and any questions feel free to ask.