document.write( "Question 904999: Rachel is driving to an appointment. at her current speed she will be 11 minutes late and her destination is still 68 miles away. she increses her speed by 6 miles per hour and arrives on time. what was her original speed? \n" ); document.write( "
Algebra.Com's Answer #548965 by ewatrrr(24785)\"\" \"About 
You can put this solution on YOUR website!
r original speed
\n" ); document.write( "68/r -68/(r+6) = 11/60 hr |Multiplying thru by r(r+6) so as all denominators = 1
\n" ); document.write( " 68*6 = (11/60)r(r+6)
\n" ); document.write( "11r^2 +66r - 60*68*6 = 0 (Tossing out the negative solution for unit measure)
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Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation \"ax%5E2%2Bbx%2Bc=0\" (in our case \"11x%5E2%2B66x%2B-24480+=+0\") has the following solutons:
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\n" ); document.write( " \"x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca\"
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\n" ); document.write( " For these solutions to exist, the discriminant \"b%5E2-4ac\" should not be a negative number.
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\n" ); document.write( " First, we need to compute the discriminant \"b%5E2-4ac\": \"b%5E2-4ac=%2866%29%5E2-4%2A11%2A-24480=1081476\".
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\n" ); document.write( " Discriminant d=1081476 is greater than zero. That means that there are two solutions: \"+x%5B12%5D+=+%28-66%2B-sqrt%28+1081476+%29%29%2F2%5Ca\".
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\n" ); document.write( " \"x%5B1%5D+=+%28-%2866%29%2Bsqrt%28+1081476+%29%29%2F2%5C11+=+44.2700174048471\"
\n" ); document.write( " \"x%5B2%5D+=+%28-%2866%29-sqrt%28+1081476+%29%29%2F2%5C11+=+-50.2700174048471\"
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\n" ); document.write( " Quadratic expression \"11x%5E2%2B66x%2B-24480\" can be factored:
\n" ); document.write( " \"11x%5E2%2B66x%2B-24480+=+11%28x-44.2700174048471%29%2A%28x--50.2700174048471%29\"
\n" ); document.write( " Again, the answer is: 44.2700174048471, -50.2700174048471.\n" ); document.write( "Here's your graph:
\n" ); document.write( "\"graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+11%2Ax%5E2%2B66%2Ax%2B-24480+%29\"
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