SOLUTION: I've tried to find these two questions and can't seem to find them. I tried to register in the students section but registered in the tutor's section. Sorry, I definitely am not tr

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Question 121721: I've tried to find these two questions and can't seem to find them. I tried to register in the students section but registered in the tutor's section. Sorry, I definitely am not trying to become a tutor. My questions:
squared 2y + 7 + 4 = y
Insulation comes in 40cm rolls that are cut to fit between the rafters in the attic. If the roof is 7m from peak to eave and the attic space is 3m high at the peak, how long does each of the pieces of insulation need to be, round to the nearest tenth. I'm sorry, i don't have the ISBN.
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
sqrt(2y + 7) + 4 = y"
sqrt(2y+7) = y-4
Square both sides to get:
2y+7 = y^2-16y+16
y^2-18y+9=0
y = [18 +- sqrt(18^2-4*9)]/2
y = [18 +- sqrt(288)]/2
y = [18 +- 16.9706]/2
y = 17.4853 or y = 0.5147
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Cheers,
Stan H.