The expression is (15+6) */* 3. This is because we add up all the costs to get the total, and divide the total by three because there are three friends splitting the cost.
Start by writing the system down, I will use
to represent 

Substitute the fact that
into the first equation to get,

Simplify into a quadratic form (
),

Now you can use Vieta's rule which states that any quadratic equation can be written in the following form,

which then must factor into

And the solutions will be
.
Clearly for small coefficients like ours
, this is very easy to figure out. To get 5 and 6 we simply say that
.
This fits the definition as
and
.
So as mentioned, solutions will equal to
but these are just x-values in the solution pairs of a form
.
To get y-values we must substitute 3 for x in the original equation and then also 2 for x in the original equation. Luckily we already know that substituting either of the two numbers yields a zero.
So the solution pairs are
and
.
Hope this helps :)
Answer:
<h2>i need to see all the answers but yeah </h2>
Step-by-step explanation:
Answer:
The 90% confidence interval for population mean is 
Step-by-step explanation:
From the question we are told that
The sample mean is 
The confidence level is 
The sample size is 
The standard deviation
Now given that the confidence level is 0.90 the level of significance is mathematically evaluated as


Next we obtain the critical value of
from the standardized normal distribution table. The values is 
The reason we are obtaining critical values for
instead of that of
is because
represents the area under the normal curve where the confidence level 1 -
(90%) did not cover which include both the left and right tail while
is just considering the area of one tail which is what we required calculate the margin of error
Generally the margin of error is mathematically evaluated as

substituting values


The 90% confidence level interval is mathematically represented as

substituting values


