Question

evaluate the expression. show all steps! circle the answer. 13. 3x^4 - 5 when x = 5 14. 8m^3÷6 when m = 3 15. 200 - 3y^2 when y = 8 16. 5c^2 - 2c when c = 9 17. 3 * 18t^2 when t = 1/2 18. 42/n + n when n = 6 19. 7(x + 5) when x = 10 20. 5a/(a - 6) when a = 8 21. 4d^2/(d + 1) when d = 3

Explanation:

Step1: Substitute x = 5 into 3x⁴ - 5

$3\times5^{4}-5$

Step2: Calculate 5⁴

$5^{4}=5\times5\times5\times5 = 625$

Step3: Multiply by 3

$3\times625=1875$

Step4: Subtract 5

$1875 - 5=1870$

Step1: Substitute m = 3 into 8m³÷6

$8\times3^{3}\div6$

Step2: Calculate 3³

$3^{3}=3\times3\times3 = 27$

Step3: Multiply by 8

$8\times27 = 216$

Step4: Divide by 6

$216\div6=36$

Step1: Substitute y = 8 into 200 - 3y²

$200-3\times8^{2}$

Step2: Calculate 8²

$8^{2}=8\times8 = 64$

Step3: Multiply by 3

$3\times64 = 192$

Step4: Subtract from 200

$200-192 = 8$

Step1: Substitute c = 9 into 5c² - 2c

$5\times9^{2}-2\times9$

Step2: Calculate 9²

$9^{2}=9\times9 = 81$

Step3: Multiply 5 by 81 and 2 by 9

$5\times81=405$, $2\times9 = 18$

Step4: Subtract

$405-18=387$

Answer:

1870