Answer: A; 6.3%
Step-by-step explanation:
Problem 1
For the first problem, we first want to find y so that we can plug it into the expression.
We can use elimination method for the system of equations to solve.
3x+3y=21
3x-y=5
We subtract both equations to eliminate x.
4y=16 [divide both sides by 4]
y=4
Now that we know y, we can plug it into the expression.
[divide]
[subtract]
We know that the answer is A.
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Problem 2
For the second problem, we need to know how to calculate percent error. The formula for precent error is 
. We know that the exact value is 80 because the buyer was supposed to given 80. 75 is the measured value because that was what the buyer was given.
[subtract]
[solve absolue value]
[divide]
[multiply]
Since the problem said to round to one decimal place, we know that the answer is 6.3%.
So you have x^3 - 4x = 0. What you can do is pull out an x from both x^3 and - 4x so it looks like this:
Then you can find a number that makes the part inside the parentheses turn into zero. For beginners, it may be easier to write it out seperately and solve for x.
We need to solve for x, so the first step is to add 4 to both sides, so we get something like this:
Then, we can square root both sides to get rid of the power on the x, so it looks like this:
Now, every square root has two answers, a positive and a negative. If we look at the bottom example:
We can see that both -2 and 2 to the power of two will equal to 4.
So finally, we get:
These are the other 'Zero's for the original function. If you are not sure of what a 'Zero' is, it is where the function crosses over the x-axis on a graph.
Answer:
The second regon
Step-by-step explanation:
Hello,
I suppose equations are:
x+y=3 (1)
x+2y=9 (2)
(2)-(1)==>y=6
(1)==>x=3-6
x=-3, y=6
Sol={(-3,6)}
