For questions 17–21, simplify the expression.

17. 7t4 • 7t4

49t8
14t4
49t16
14t8

18. –3(4x + 5)

7x + 15
7x – 15
–12x – 15
–12x + 15

19. 5k2(–6k2 – 2k + 6)

–30k3 + 3k2 + 30k
30k4 – 10k3 + 11k2
–k4 + 3k3 + 11k2
–30k4 – 10k3 + 30k2

20. (–8x) • 3x2

–5x3
–24x2
–24x3
–5x2
21. (7y2 – 3y) + (8y2 – 8y)

56y2 – 24y
15y2 – 11y
–y2 + 5y
y2 – 5y

MY ANSWERS
17. A
18. C
19. D
20. ?
21. B

20 (C)

Odd that you could get 19, but got stuck on 20

I know it was confusion for me did i get them all right?

yes, except 20.

ok thanks

Thx

How do you miss #20

Let's go through each of the expressions and simplify them one by one:

17. To simplify the expression 7t^4 • 7t^4, we need to multiply the coefficients (7 • 7) and add the exponents (t^4 • t^4). This gives us 49t^(4+4), which simplifies to 49t^8. Therefore, the correct answer is 49t^8, which corresponds to option C.

18. To simplify the expression -3(4x + 5), we need to distribute the -3 to both terms inside the parentheses. This gives us -3 * 4x + -3 * 5, which simplifies to -12x - 15. Therefore, the correct answer is -12x - 15, which corresponds to option C.

19. To simplify the expression 5k^2(-6k^2 - 2k + 6), we need to distribute the 5k^2 to each term inside the parentheses. This gives us 5k^2 * -6k^2 + 5k^2 * -2k + 5k^2 * 6. Simplifying each term individually, we get -30k^(2+2) - 10k^(2+1) + 30k^2, which simplifies to -30k^4 - 10k^3 + 30k^2. Therefore, the correct answer is -30k^4 - 10k^3 + 30k^2, which corresponds to option D.

20. To simplify the expression (-8x) • 3x^2, we need to multiply the coefficients (-8 • 3) and add the exponents (x^1 • x^2). This gives us -24x^(1+2), which simplifies to -24x^3. Therefore, the correct answer is -24x^3, which corresponds to option C.

21. To simplify the expression (7y^2 - 3y) + (8y^2 - 8y), we need to combine like terms. Adding the coefficients and keeping the exponents the same, we get 7y^2 + 8y^2 - 3y - 8y. Simplifying further, we have 15y^2 - 11y. Therefore, the correct answer is 15y^2 - 11y, which corresponds to option B.

Based on the above explanations, the correct answers are:
17. C
18. C
19. D
20. C
21. B