The rise or an increase in altitude is represented by positive sign and a decend or decrease in altitude is represented by negative sign.
First the helicopter descended 1200 feet. So the change in altitude will be -1200 feet.
Then the helicopter rose by 800 feet. So the change in altitude will be 800 feet.
Finally the helicopter descended by 450 feet. So the change in altitude will be -450 feet.
The net change in altitude will be the sum of all the above 3 changes.
Change in altitude = -1200 + 800 - 450 = -850 feet
The negative sign indicates a descend i.e. loss in altitude. So the net change in altitude was a loss of 850 feet.
quadratic formula:
x = <u>-b ± √(b² - 4ac)</u>
2a
7x² - x = 7
subtract 7 from both sides:
7x² - x - 7 = 0
plug values into the quadratic formula:
x = <u>-(-1) ± √((-1)²- 4(7)(-7))</u>
2(7)
simplify:
x = <u>1 ± √(197)</u>
14
Answer: #20, x = 3
#21, x = 1/2
Step-by-step explanation:
#20) x + 4 + x + 2+ x + 5 = x + 3 +x+3+x+1+x+1
3x + 11 = 4x + 8
<u>-3x -3x</u>
11= x + 8
<u> - 8 - 8</u>
3 = x
#21) 12x(5) = 6x + 9 + x + 10 + x + 7
60x =8x + 26
<u> -8x -8x</u>
52x = 26
divide both sides by 52
x = 1/2
Because the parabola opens down and the vertex is at (0, 5), we conclude that the correct option is:
y = -(1/8)*x² + 5.
<h3>
Which is the equation of the parabola?</h3>
The relevant information is that we have the vertex at (0, 5), and that the parabola opens downwards.
Remember that the parabola only opens downwards if the leading coefficient is negative. Then we can discard the two middle options.
Now, because the parabola has the point (0, 5), we know that when we evaluate the parabola in x = 0, we should get y = 5.
Then the constant term must be 5.
So the correct option is the first one:
y = -(1/8)*x² + 5.
If you want to learn more about parabolas:
brainly.com/question/4061870
#SPJ1
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