SOLUTION: The path of a basketball can be described by the equation y = -16t2 + 18t + 7, where y is the height of the basketball and t is the time in seconds it is in the air. After the bask

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Question 921182: The path of a basketball can be described by the equation y = -16t2 + 18t + 7, where y is the height of the basketball and t is the time in seconds it is in the air. After the basketball is thrown, how much time passes before it passes through the basket, which is 10 feet off the ground? Round your answer to the nearest hundredth of a second.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The basketball can't go through the basket while
it is on the way up ( y increasing ). It has to reach it's
maximum height, and then go through the basket
on the way down ( y decreasing )
-------------------------------
+y+=+-16t%5E2+%2B+18t+%2B+7+
+10+=+-16t%5E2+%2B+18t+%2B+7+
+-16t%5E2+%2B+18t+-+3+=+0+
Use the quadratic formula
+t+=+%28+-b+%2B-+sqrt%28++b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+
+a+=+-16+
+b+=+18+
+c+=+-3+
+t+=+%28+-18+%2B-+sqrt%28++18%5E2+-+4%2A%28-16%29%2A%28-3%29+%29%29+%2F+%282%2A%28-16%29%29+
+t+=+%28+-18+%2B-+sqrt%28++324+-+192+%29%29+%2F+%28-32%29+
+t+=+%28+-18+%2B-+sqrt%28++132+%29%29+%2F+%28-32%29+
+t+=+%28+-18+%2B+11.489+%29+%2F+%28-32%29+
+t+=+.2035+ sec
This is when the basketball is on the way up, just after
it leaves the shooters hand
The other value for +t+ should be when it is going
through the basket on the way down
+t+=+%28+-18+-+11.489+%29+%2F+%28-32%29+
+t+=+29.489%2F32+
+t+=+.9215+ sec
Rounded off:
+t+=+.92+ sec
----------------
Here's the plot:
+graph%28+400%2C+400%2C+-.5%2C+1.5%2C+-1%2C+14%2C+-16x%5E2+%2B18x+%2B+7+%29+