Answer:
Step-by-step explanation:
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Answer:
x = 0, y = 7
Step-by-step explanation:
Solving a system of equations using substitution requires one side to be equal to a variable present in the equation, in this case x or y. We should simplify the equation using elimination before substituting to reduce the chance of error.
In order to use the elimination method, you have to create variables that have the same coefficient—then you can eliminate them. These equations arew already aligned for us.
3x - 10y=-70
-<u> 4x +9y = 63</u>
-x + y = 7
Now, for substitution, the equation must be set to a variable.
-x + y = 7
y = x + 7
Next, plug the equation in where applicable in another equation.
4x +9(x + 7) = 63
4x + 9x + 63 = 63
13x = 0
x = 0
The final step of substitution is to plug the known variable into an equation to find the other variable.
3(0) - 10y=-70
0 - 10y = -70
10y = 70
y = 7
I guarantee you this answer is correct, I worked it out using other methods and graphing prior to submitting this answer.
Some expressions are:
7 times 4 equals 28
20 plus 8 equals 28
10 plus 18 equals 28
25 plus 3 equals 28
Observe that as the series progresses, the term decreases by 1/4. To show this, observe the first four terms of the series below.
-200 = (1/4)(-800)
-50 = (1/4)(-200)
-12.5 = (1/4)(-50)
Since we have a common ratio, r, of 1/4, we can use the properties of a geometric series to find the 8th term of the series.
Recall that to find the sum of the nth term of a geometric series, we have

where a is the first term of the series and r is the ratio.
So, for the first eight terms, we have


Therefore, the sum of the 8th series is approximately -1066.65.
Answer: -1066.65