SOLUTION: 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

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: 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      Log On


   

Question 1155399: 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 by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
Just to pick two of them and solving:

#4
-+x%5E3+%2B+22x%5E2+-+121x+=+0
-x%28x%5E2+-+22x+%2B+121%29+=+0
-x+%28x+-+11%5E2%29+=+0
-x+%28x+-+11%29%2A+%28+x+%2B+11%29+=0
Look there and see THREE factors to equate to 0.
They are 0, 11, & -11.



#15.
The product of two consecutive positive integers is 72. Find the integers.
n%28n+%2B+1%29=+72
If you do not need to solve a quadratic equation then basic fact is 72=9*8, so the solution is n=8.
(OR, -9 and -8 are the two factors, so n=-9 OR n=8)

If you are required to use as quadratic equation and solve, then n%5E2%2Bn-72=0
and you could factorize into %28n%2B9%29%28n-8%29=72


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Those two ARE done for you, STEP-BY-STEP.