You put the x=6
6³-4(6)²-12(6)+15=15
Given QR is congrent to LN and QR = 4x + 2 and LN = x + 7.
So, QR = LN
Hence, we can set up an equation as following:
4x + 2 = x + 7
4x + 2 - x = x + 7 - x Subtract x from each sides.
3x + 2 = 7 By simplifying.
3x + 2 - 2 = 7 - 2 Subtract 2 from each sides.
3x = 5
Divide each sides by 3 to isolate x.
So, 
Next step is to plug in
in QR = 4x+2 to get length of QR.
So, 
Since 2 can be written as 2/1.
By multiplying the second fraction by the common denominator 3.
By simplifying the second fraction.

So, 
The answer to this is 1/3
Answer:
SA = 2520 ft^2
Step-by-step explanation:
a = 21ft
b = 29ft
c = 20ft
h = 30ft
SA = 2
+ (a+b+c)h
= s(s﹣a)(s﹣b)(s﹣c)
s = 
SA= ah + bh + ch +

SA= (21 * 30) + (29 * 30) + (20 * 30) +

SA = 2520 ft^2
Part a)
Answer: 5*sqrt(2pi)/pi
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Work Shown:
r = sqrt(A/pi)
r = sqrt(50/pi)
r = sqrt(50)/sqrt(pi)
r = (sqrt(50)*sqrt(pi))/(sqrt(pi)*sqrt(pi))
r = sqrt(50pi)/pi
r = sqrt(25*2pi)/pi
r = sqrt(25)*sqrt(2pi)/pi
r = 5*sqrt(2pi)/pi
Note: the denominator is technically not able to be rationalized because of the pi there. There is no value we can multiply pi by so that we end up with a rational value. We could try 1/pi, but that will eventually lead back to having pi in the denominator. I think your teacher may have made a typo when s/he wrote "rationalize all denominators"
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Part b)
Answer: 3*sqrt(3pi)/pi
-----------------------
Work Shown:
r = sqrt(A/pi)
r = sqrt(27/pi)
r = sqrt(27)/sqrt(pi)
r = (sqrt(27)*sqrt(pi))/(sqrt(pi)*sqrt(pi))
r = sqrt(27pi)/pi
r = sqrt(9*3pi)/pi
r = sqrt(9)*sqrt(3pi)/pi
r = 3*sqrt(3pi)/pi
Note: the same issue comes up as before in part a)
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Part c)
Answer: sqrt(19pi)/pi
-----------------------
Work Shown:
r = sqrt(A/pi)
r = sqrt(19/pi)
r = sqrt(19)/sqrt(pi)
r = (sqrt(19)*sqrt(pi))/(sqrt(pi)*sqrt(pi))
r = sqrt(19pi)/pi