путешествиники добирались до города 3 часа на автобусе 7 часов на поезде и 5 часов плили на лодке сколько всего часов они были в
1 answer:
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Answer:
(x, y) ≈ (2.848, -19.241)
Step-by-step explanation:
I find it much easier to work with the problem statement when math expressions are written using numbers and symbols. We assume you have ...
-4x +15y = -300
20x +4y = -20
Dividing the second equation by 4 and subtracting the x-term gives ...
y = -5-5x
Substituting that into the first equation, we get ...
-4x +15(-5-5x) = -300
-79x -75 = -300
x = -225/-79 = 2 67/79 ≈ 2.8481
Substituting this into the equation for y gives ...
y = -5(x +1) = -5(3 67/79) = -19 19/79 ≈ -19.2405
The approximate solution is ...
(x, y) = (2.8481, -19.2405)
9514 1404 393
Answer:
D.
Step-by-step explanation:
The wording "when x is an appropriate value" is irrelevant to this question. That phrase should be ignored. (You may want to report this to your teacher.)
When you look at the answer choices, you see that all of them are negative except the last one (D). When you look at the problem fraction, you see that it is positive.
The only reasonable choice is D.
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Your calculator can check this for you.
√12/(√3 +3) ≈ 3.4641/(1.7321 +3)
= 3.4641/4.7321 ≈ 0.7321 = -1 +√3
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If you want to "rationalize the denominator", then multiply numerator and denominator by the conjugate of the denominator. The conjugate is formed by switching the sign between terms.
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<em>Additional comment</em>
We "rationalize the denominator" in this way to take advantage of the relation ...
(a -b)(a +b) = a² -b²
Using this gets rid of the irrational root in the denominator, hence "rationalizes" the denominator.
We could also have multiplied by (3 -√3)/(3 -√3). This would have made the denominator positive, instead of negative. However, I chose to use (√3 -3) so you could see that all we did was change the sign from (√3 +3).