Answer:
r(-1) = 6.31 and r(2) = -16.88
Explanation:
* Lets read the problem and solve it
- Evaluate means find the value, so evaluate r(x) means find the value
of it at the given values of x
∵ r(x) = -0.21x³ + x² - 8.1x - 3
∵ x = -1 and x = 2
- Then find r(-1) by substitute x by -1 and find r(2) by substitute x by 2
# At x = -1
∴ r(-1) = -0.21(-1)³ + (-1)² - 8.1(-1) - 3
∴ r(-1) = -0.21(-1) + (1) - 8.1(-1) - 3
∴ r(-1) = 0.21 + 1 + 8.1 - 3
∴ r(-1) = 6.31
# At x = 2
∴ r(2) = -0.21(2)³ + (2)² - 8.1(2) - 3
∴ r(2) = -0.21(8) + (4) - 8.1(2) - 3
∴ r(2) = -1.68 + 4 - 16.2 - 3
∴ r(2) = -16.88
* r(-1) = 6.31 and r(2) = -16.88