Answer:
2.5 seconds.
Step-by-step explanation:
Find the value of t when the height is 28 feet:
-16t^2 + 56t + 4 = 28
-16t^2 + 56t - 24 = 0
-8(2t^2 - 7t + 3) = 0
-8(2t - 1)(t - 3) = 0
t = 0.5, 3 seconds.
So on the upward journey the rock is at 28 feet at 0.5 second after the throw and at 3 seconds it is at 28 feet again while it is falling back.
Therefore the period when it is at least 28 feet above the ground is 3.0 - 0.5 = 2.5 seconds.
Answer:
≈ 58
Step-by-step explanation:
Estimation usually means you want an answer good to one or maybe two significant figures. That usually means you want to round the numbers involved to one or two significant figures.
Doing that here transforms the problem to 180/3 = 60, an answer with one significant figure.
You can improve the estimate a bit by recognizing that it is a little high (the numerator is higher than 175.32, but the denominator is the same). Since the numerator is high by about 5, the estimate is high by about 5/3 or a little less than 2. A closer estimate will be 60 - 2 = 58.
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The degree to which you refine the estimate will depend on the error requirements you have. Certainly an estimate of 60 is within 10% of the true value, so is "close enough" for many purposes.
Answer:
First one
Step-by-step explanation:
–6<span>x2</span> – x + 2 = –1(6<span>x2</span> + x – 2)<span>. I hope this helped ^^</span>