Answer:
4. -2s^9
7. 8b^10
Explanation:
First, focus on the number part of the expression. For 4), multiply -2 x -1 x -1 = -2. Then, look at the exponents. When you're multiplying exponents with the same base (in number 4, the base is s), you can add the exponents.
2+3+4 = 9; which makes it s^9. Multiply -2 x s^9, which gives you -2s^9.
Same thing for 7). Multiply all the numbers first. this gives you 8. (Remember two negatives equals a positive). Add all of the exponents of b together, which gives you 10. (when a variable has no exponent, it means that the exponent is 1.) Multiplying 8 and b^10 should give you 8b^10.
It may help to brush up on exponent rules and sign rules.