Question

Please help me fix these

My teachers response:
4. You had it in your 3rd step. I'm not sure why you included the last step. What would each of those x's from your 3rd step be worth if you solved for each of them.

15. 8 is one of them, what is the second number?

18. Not quite. Please explain what each number represents and how you will know if it is + or -.

19, 20. Recalculate





Solve the quadratic equations in questions 1 – 5 by factoring.

4. –x^3 + 22x^2 – 121x = 0

-x (x^2 - 22x + 121) = 0

-x (x - 11^2) = 0

-x (x - 11)* ( x + 11) =0

Solutions: x= 11, x= -11

15. The product of two consecutive positive integers is 72. Find the integers.

n(n + 1)= 72

n^2 + n = 72

n^2 + n - 72 = 0

n= -b±√b^2 - 4ac ÷ 2a

n= -(1)±√(1)^2 - 4 (1)(-72)÷ 2*1

n= -1±√1 + 288÷2

n= -1±√289÷2

n= -1±17 ÷ 2

n= -1 + 17 ÷ 2 N= -1 - 17÷ 2

n= 16÷2 N= -18÷ 2

n= 8 N= -9

Answer = 8



18. A tennis ball is launched straight upward with an initial velocity of 24.5 m/s from the edge of a cliff that is 117.6 meters above the ground. Which quadratic equation could be used to correctly determine when the ball will hit the ground:



4.9t^2 + 24.5t + 117.6 = 0



-4.9t^2 - 24.5t + 117.6 = 0



-4.9t^2 + 24.5t - 117.6 = 0



4.9t^2 + 24.5t - 117.6 = 0



-4.9t^2 + 24.5t + 117.6 = 0



Answer: 4.9t^2 + 24.5t - 117.6 = 0





19. Solve the equation you chose in question 18 to determine when the ball will hit the ground. (HINT: If you don't get one of the answers listed for this question, then maybe you chose the wrong equation in #18. Use this opportunity to double check your work!)



t = 8 seconds



t = 4 seconds



t = 3 seconds



t = -3 seconds



The ball will never reach the ground.



4.9 x 9 + 24.5 x 3 - 117.6 = 0



Answer is: 3



20. Using the same equation, determine when the ball is at a height of 49 meters.





4.9t² + 24.5t - 49 = 0



Solve for t

t = (-24.5 ±√[ 24.5² - 4 x 4.9 x - 49])/9.8



t =1.53 seconds

04/06/2020 14:21

Samantha,

4. You had it in your 3rd step. I'm not sure why you included the last step. What would each of those x's from your 3rd step be worth if you solved for each of them.

15. 8 is one of them, what is the second number?

18. Not quite. Please explain what each number represents and how you will know if it is + or -.

19, 20. Recalculate

Answer 1

Answer: See below

Explanation:

4) You made an error in step 3

Step 1: -x³ + 22x² - 121x = 0

Step 2: -x(x² - 22x + 121) = 0

Step 3: -x(x - 11²) = 0 Error!

-x(x - 11)² = 0 Correction

Step 4: -x = 0 (x - 11)² = 0

Step 5: x = 0 x = 11

15) Your work is correct

n = 8, n = -9 BOTH answers are correct

Answer: n = 8 Error!

n = 8, n = -9 Correction

18) The formula is: h(t) =at² + vt + h(0)

• a = -4.9 acceleration is negative because gravity pushes down
• v = 24.5 velocity is positive because it states it is "upward"
• h(0) = 117.6 h(0) is initial height

Answer: h(t) = -4.9t² + 24.5t + 117.6 option 3

19) Now that you have the correct equation, you can use the quadratic formula to solve for t

t = -3, t = 8

Since time cannot be negative, t = -3 is not valid

Answer: t = 8 option 1

20) It is given that h(t) = 49

Equation: 49 = -4.9t² + 24.5t + 117.6

0 = -4.9t² + 24.5t + 68.6

Use the quadratic equation to solve: t = -2, t = 7

Since time cannot be negative, t = -2 is not valid

Answer: t =7