The equation of the first line can be written in point-slope form as
.. y = 3(x +1) -8
or
.. 3x -y = 5
The equation of the second line can be written in 2-point form as
.. y = (-1-3)/(10-(-6))*(x +6) +3
.. y = (-1/4)(x +6) +3
or
.. x +4y = 6
A graph shows the solution to this system is (x, y) = (2, 1).
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The second equation can be used to write an expression for x:
.. x = 6 -4y
This can be substituted into the first equation.
.. 3(6 -4y) -y = 5
.. 18 -13y = 5 . . . . . . . collect terms
.. 13 = 13y . . . . . . . . . add 13y-5
.. 1 = y . . . . . . . . . . . . divide by 13
From the above equation for x
.. x = 6 -4*1 = 2
Answer: 30 couples.
Justification:
You can follow a systematic approach to tackle this kind of problems.
Construct a chain of ratios whose units cancel out to yield to a result with the right units of the answer you are looking for.
In this case you want to know the number of couples that took the ride in 30 minutes.
The input data are:
1 couple / seat
1 seat / minute
Then, by multiplying those two data you get: [1 couple / seat] * [1 seat / minute], which, treating the units appropiately yields to 1 couple / minute.
Next, you realize that when you muliply 1 couple / minute times the number of minutes you get the number of couples that took the ride in that time.
So, the answer is: 1 couple / minute * 30 minute = 30 couples (the minutes cancel out because they appear in the denominator and numerator).
So, when you work with ratios and proportions, the use of units helps you a lot to figure out the way to get the answer.
(X)=2X-ALL real numbers except x=0x<_0
Answer:
C
Reasoning:
You should add a period to fix the run-on sentence because they're two different ideas. (They don't fit in the same sentence.)
Expression: 5+5
Equation: 5a + 2b =5
Inequality: 2x > 2+5