For this case we have the following variable:
p: cost of the item that Arthur wants to buy before tax
The expression for the 6% tax is given by:
Or equivalently:
Therefore, two different expressions for the total cost are:
Expression 1:
Expression 2:
To prove that they are equal, suppose that the item costs $ 100:
Expression 1:
Expression 2:
Since the cost is the same, then the expressions are the same.
Answer:
Two different expressions that model the problem are:
M=2 do need a step by step explanation?
Answer:
x = 84/5 = 16.8
Step-by-step explanation:
The angle bisector theorem said that
21/15 = x/12
==> 7/5 = x/12
==> x = 84/5
Answer:
C. 3.33 hours
Step-by-step explanation:
Use the algebra work equation:
= 
+ 
, where tb is the time to work together, t1 is the time it takes one person, and t2 is the time it takes the other person
Plug in the values we know:
= 
+ 
= 
+ 
= 
20 = 6tb
3.33 = tb
So, it would take them 3.33 hours when working together.
Answer:
x = √(a(a+b))
Step-by-step explanation:
We can also assume a > 0 and b > 0 without loss of generality. (If a and a+b have opposite signs, the maximum angle is 180° at x=0.)
We choose to define tan(α) = -(b+a)/x and tan(β) = -a/x. Then the tangent of ∠APB is ...
tan(∠APB) = (tan(α) -tan(β))/(1 +tan(α)tan(β))
= ((-(a+b)/x) -(-a/x))/(1 +(-(a+b)/x)(-a/x))
= (-bx)/(x^2 +ab +a^2)
This will be maximized when its derivative is zero.
d(tan(∠APB))/dx = ((x^2 +ab +a^2)(-b) -(-bx)(2x))/(x^2 +ab +a^2)^2
The derivative will be zero when the numerator is zero, so we want ...
bx^2 -ab^2 -a^2b = 0
b(x^2 -(a(a+b))) = 0
This has solutions ...
b = 0
x = √(a(a+b))
The former case is the degenerate case where ∠APB is 0, and the value of x can be anything.
The latter case is the one of interest:
x = √(a(a+b)) . . . . . . the geometric mean of A and B rotated to the x-axis.
_____
<em>Comment on the result</em>
This result is validated by experiments using a geometry program. The location of P can be constructed in a few simple steps: Construct a semicircle through the origin and B. Find the intersection point of that semicircle with a line through A parallel to the x-axis. The distance from the origin to that intersection point is x.
