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Seph
09-16-2009, 05:16 PM
Can anyone help me with the following problems

25 over x - 21 over x-2 +2 =0

(x + 8)2 - 8(x + 8) + 15 = 0

Two television monitors sitting beside each other on a shelf in an appliance store have the same screen height. One has a conventional screen, which is 3 inches wider than it is high. The other has a wider, high-definition screen, which is 1.8 times as wide as it is high. The diagonal measure of the wider screen is 14 inches more than the diagonal measure of the smaller. What is the height of the screens, correct to the nearest 0.1 inch?

car rental company offers two plans for renting a car.
Plan A: $20 per day and 23˘ per mile
Plan B: $60 per day with free unlimited mileage
For what range of miles will plan B save you money? Give your answer as an interval (in miles). (Round the answer to the nearest lower whole mile.)

acdcfanbill
09-16-2009, 07:38 PM
25 over x - 21 over x-2 +2 =0

(25(x-2))/(x(x-2)) - (21x)/((x-2)x) + (2x^2-4x)/(x(x-2) = 0 (give everything to the left of the = a common denominator)

((25x-50)-21x+(2x^2-4x))/(x(x-2)) = 0 (simplify)

(2x^2-50)/(x(x-2)) = 0

2x^2-50=0 --> x = sqrt(25)


(x + 8)2 - 8(x + 8) + 15 = 0

(x+8)(2-8) + 15 = 0 (I factored out the (x+8), you could distribute the 2 and -8 if you like)

-6x + -48 + 15 = 0

-6x + -33 = 0 => -6x = 33 => x = (-33/6) = -5.5


Two television monitors sitting beside each other on a shelf in an appliance store have the same screen height. One has a conventional screen, which is 3 inches wider than it is high. The other has a wider, high-definition screen, which is 1.8 times as wide as it is high. The diagonal measure of the wider screen is 14 inches more than the diagonal measure of the smaller. What is the height of the screens, correct to the nearest 0.1 inch?

This is an awful question (in that widescreen tv's are a ratio of 16:9 which is 1.7 repeating), but just pull out the equations you can see...

h1 = h2 = h (same height)
tv1: w1 = h+3
tv2: w2 = h(1.8)

d2 = d1 + 14

tv1: (d1)^2 = (h)^2 + (w1)^2
tv2: (d2)^2 = (h)^2 + (w2)^2


Then do a simultaneous equation solve, substitution looks easy enough. (h+3) in for w1, h(1.8) in for w2 and d1+14 for d2. You should be able to work that out.



car rental company offers two plans for renting a car.
Plan A: $20 per day and 23¢ per mile
Plan B: $60 per day with free unlimited mileage
For what range of miles will plan B save you money? Give your answer as an interval (in miles). (Round the answer to the nearest lower whole mile.)

again, pick out the equations...

m=miles, t=total cost
a: 20 + .23m = t
b: 60 = t

solve by substitution again.

JesusIsGonnaOwnSatan
09-16-2009, 10:10 PM
Aaaaalgebraaah

:golfclap:

Seph
09-17-2009, 01:55 AM
Thanks man, but it's still not sticking, algebra is the only class that I pretty much can't do

Anthony
09-17-2009, 06:52 PM
thanks, now i have a headache