See the attached picture showing the work:
The answer is (x+7)(x-4)
hence, the solution should be C
Answer:
- 1.25 hours or 1 hour and 15 minutes
Step-by-step explanation:
<em>Question</em>
- <em>Lisa lit a candle with a height of 8 inches. When lit, this candle loses 10% of its original height every hour. </em>
- <em>Please complete the following sentence by writing the number in the blank.
Until the candle has been burning for at least _______ hours, the height of Jennifer's candle will be more than 7 inches.</em>
<u>Candle looses 10% of 8 inches, it equals:</u>
- 8*0.1 = 0.8 inches an hour
<u>Let x be required time, then:</u>
- 8 - 0.8x > 7
- 0.8x < 8 - 7
- 0.8x < 1
- x < 1/0.8
- x < 1.25
- or 1 hour 15 minutes
We are given original equation: ![x^2 -10x + y^2 + 12y = 20](https://tex.z-dn.net/?f=x%5E2%20-10x%20%2B%20y%5E2%20%2B%2012y%20%3D%2020)
We need to find the enter and radius of a circle using the completing the square method.
The steps are as following :
Step 1 [original equation]: x^2 − 10x + y^2 + 12y = 20 .
Step 2 [group like terms]: (x^2 − 10x) + (y^2 + 12y) = 20
Step 3 [complete the quadratics]: (x^2 − 10x + 25) + (y^2 + 12y + 36) = 20 + (25 + 36).
Step 4 [simplify the equation]: (x^2 − 10x + 25) + (y^2 + 12y + 36) = 64.
Step 5 [factor each quadratic]: (x − 5)^2 + (y + 6)^2 = 8^2
Step 6 [identify the center and radius]: Center = (5, −6) Radius = 8.
<h3>Step 6 is incorrect.</h3><h3>The center should be (5,-6).</h3><h3> Replace − 5 with + 5 and replace + 6 with − 6.</h3>