Answer:
3x³ + 12x
Explanation:
3x is 3 times x. If we multiply x times x², we get x³. This is because x² can be written as x·x, so if we multiply x by that, we get x·x·x. Since we are multiplying x² by 3x, we get 3x³. Now, we multiply 3x by 4, this gets us 12x. Now, we write it out as 3x³ + 12x.