21 - 4x = 108
<em><u>Subtract 21 from both sides</u></em>
-4x = 87
<em><u>Divide both sides by -4</u></em>
x = -21.75
Answer:
Well if you are trying to find the length of each side you Divide 24 by 4 so your answer would be 6
Step-by-step explanation:
Answer:
- (x, y) = (3, 5)
- (x, y) = (1, 2)
Step-by-step explanation:
A nice graphing calculator app makes these trivially simple. (See the first two attachments.) It is available for phones, tablets, and as a web page.
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The usual methods of solving a system of equations involve <em>elimination</em> or <em>substitution</em>.
There is another method that is relatively easy to use. It is a variation of "Cramer's Rule" and is fully equivalent to <em>elimination</em>. It makes use of a formula applied to the equation coefficients. The pattern of coefficients in the formula, and the formula itself are shown in the third attachment. I like this when the coefficient numbers are "too messy" for elimination or substitution to be used easily. It makes use of the equations in standard form.
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1. In standard form, your equations are ...
Then the solution is ...
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2. In standard form, your equations are ...
Then the solution is ...
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<em>Note on Cramer's Rule</em>
The equation you will see for Cramer's Rule applied to a system of 2 equations in 2 unknowns will have the terms in numerator and denominator swapped: ec-bf, for example, instead of bf-ec. This effectively multiplies both numerator and denominator by -1, so has no effect on the result.
The reason for writing the formula in the fashion shown here is that it makes the pattern of multiplications and subtractions easier to remember. Often, you can do the math in your head. This is the method taught by "Vedic maths" and/or "Singapore math." Those teaching methods tend to place more emphasis on mental arithmetic than we do in the US.
Answer:
The 90% confidence interval for the true proportion of all consumers who favor the design is (0.52, 0.59).
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of , we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
For this problem, we have that:
90% confidence level
So , z is the value of Z that has a pvalue of , so .
The lower limit of this interval is:
The upper limit of this interval is:
The 90% confidence interval for the true proportion of all consumers who favor the design is (0.52, 0.59).