The exercise is apparently directed toward getting you to group the positive integers together and the negative integers together before you work out the difference. Doing that gives you ...
a) (10 +5) -19
b) = 15 -19
= -4
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Personally, I wouldn't do that <em>for this problem</em>. If you do the arithmetic in order, it seems easier to me because you're only doing single-digit arithmetic after the first sum.
= (10 -19) +5
= -9 +5
= -4
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The idea is that there are different stratgies that you can employ to simplify your work and reduce errors. Grouping positive and negative numbers together is one such strategy. Arranging the sums so they almost cancel is another strategy you can use.
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Good morning,</h2>
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<em><u>Answer</u></em>:
a+a+a = 3a.
4b-b = 3b.
3x²+x² = 4x².
<u><em>explanation</em></u>
a+a+a = 3a.
4b-b = b(4 - 1) = b × 3 = 3b.
3x²+x² = x²(3 + 1) = x² × 4 = 4x².
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:)
<span>6 km × 1 hour/(b-4 km) = 12 km × (1 hour/(b+4 km)
6/(b-4) hours = 12/(b+4) hours
6(b+4) = 12(b-4)
6b + 24 = 12b - 48
72 = 6b
b = 12
The boat's speed in still water is 12 km/hour.</span>
Y=2x^2 -28x+94 download math papa it will show you
The square root of -4 is the same thing as the square root of -1 times the square root of 4. The square root of 4 is 2, but the square root is an imaginary number, i. Since it is an imaginary number, it is indeterminate whether it is a rational or irrational (given current number theory) so the square root of negative 4 is neither rational nor irrational. It is imaginary.