Answer:
x=1, y=-4. (1, -4).
Step-by-step explanation:
y=-7x+3
y=-x-3
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-7x+3=-x-3
-7x-(-x)+3=-3
-7x+x=-3-3
-6x=-6
6x=6
x=6/6
x=1
y=-1-3=-4
With the given information, we can create several equations:
120 = 12x + 2y
150 = 10x + 10y
With x being the number of rose bushes, and y being the number of gardenias.
To find the values of the variables, we can use two methods: Substitution or Elimination
For this case, let us use elimination. To begin, let's be clear that we are going to be adding these equations together. Therefore, in order to get the value of one variable, we must cancel one of them out - it could be x or y, it doesn't matter which one you decide to cancel out. Let's cancel the x out:
We first need to multiply the equations by numbers that would cause the x's to cancel out - and this can be done as follows:
-10(120 = 12x + 2y)
12(150 = 10x + 10y) => Notice how one of these is negative
Multiply out:
-1200 = -120x - 20y
+ 1800 = 120x + 120y => Add these two equations together
---------------------------------
600 = 100y
Now we can solve for y:
y = 6
With this value of y known, we can then pick an equation from the beginning of the question, and plug y in to solve for x:
120 = 12x + 2y => 120 = 12x + 2(6)
Now we can solve for x:
120 = 12x + 12 => 108 = 12x
x = 9
So now we know that x = 9, and y = 6.
With rose bushes being x, we now know that the cost of 1 rose bush is $9.
With gardenias being y, we now know that the cost of 1 gardenia is $6.
The smallest region that can be photographed is
5*7 = 35 square km
so we want to know how long it takes to zoom out to an area of
35 * 5 = 175 square km.
Notice that the length and width increase at the same rate, 2 km/sec, and they start out with a difference of two, so when the width has increased from 5 to x, the length will have increased from 7 to x+2. At the desired coverage area, then,
x(x+2) = 175
x^2 + 2x = 175
x^2 + 2x + 1 = 176 [completing the square]
(x+1)^2 = 176
x+1 = ±4√11
x = -1 ±4√11
Since a negative value for x is meaningless here, x must be
-1 + 4√11 = about 12.27 km
and the time it took to increast to that value was
(12.27 - 5) km / (2 km/sec) = about 3.63 seconds
Answer:
Step-by-step explanation:
1 <em>4(1) + 2 6</em>
3 <em>4(3) + 2 14</em>
6 <em>4(6) + 2 26</em>
0 <em>0 + 3 3</em>
2 <em>2 + 3 5</em>
4 <em>4 + 3 7</em>
<em>1 1 - 1 </em> 0
<em>3 3 - 1</em> 2
<em>5 5 - 1</em> 4
It is 165 I hope this helps :)
