Extra Credit Do the following for each equation or inequality. (5 points total) (i) Indicate if the graph is a curve, surface, or solid. (ii) Draw a sketch of the graph of the equation or inequality. 7. 3x + 4y + 6z = 12 8. r(t) = (2i+j+ 3k)t 9. The region bounded by z = 0, z = 4-x², y = 0, y = 3.