document.write( "Question 821393: On a recent trip Sarah's car traveled 20 mph faster on the first 130 miles than it did on the remaining 80 miles. The total time for the trip was 4 hours. Find the speed of Sarah's car on the first part of the trip. \n" ); document.write( "
Algebra.Com's Answer #494072 by TimothyLamb(4379)\"\" \"About 
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\n" ); document.write( "t = d / s
\n" ); document.write( "---
\n" ); document.write( "stage1:
\n" ); document.write( "x = 130/s
\n" ); document.write( "---
\n" ); document.write( "stage2:
\n" ); document.write( "y = 80/(s - 20)
\n" ); document.write( "---
\n" ); document.write( "total time = 4 = x + y
\n" ); document.write( "4 = 130/s + 80/(s - 20)
\n" ); document.write( "4 = 130(s - 20)/s(s - 20) + 80s/s(s - 20)
\n" ); document.write( "4s(s - 20) = 130(s - 20) + 80s
\n" ); document.write( "4ss - 80s = 130s - 2600 + 80s
\n" ); document.write( "4ss - 290s + 2600 = 0
\n" ); document.write( "---
\n" ); document.write( "the above quadratic equation is in standard form, with a=4, b=-290, and c=2600
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\n" ); document.write( "to solve the quadratic equation, by using the quadratic formula, copy and paste this:
\n" ); document.write( "4 -290 2600
\n" ); document.write( "into this solver: https://sooeet.com/math/quadratic-equation-solver.php
\n" ); document.write( "---
\n" ); document.write( "the two real roots (i.e. the two x-intercepts), of the quadratic are:
\n" ); document.write( "s = 62.0194102
\n" ); document.write( "s = 10.4805898
\n" ); document.write( "---
\n" ); document.write( "recall that speed on stage2 is (s - 20), so the second root (s ~= 10.48) would make the speed for stage2 negative (10.48 - 20), which doesn't make sense, therefore, we use the first root (s ~= 62.02)
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\n" ); document.write( "answer:
\n" ); document.write( "the speed of Sarah's car on the first part of the trip = 62.02 mph
\n" ); document.write( "---
\n" ); document.write( "Solve and graph linear equations:
\n" ); document.write( "https://sooeet.com/math/linear-equation-solver.php
\n" ); document.write( "---
\n" ); document.write( "Solve quadratic equations, quadratic formula:
\n" ); document.write( "https://sooeet.com/math/quadratic-formula-solver.php
\n" ); document.write( "---
\n" ); document.write( "Solve systems of linear equations up to 6-equations 6-variables:
\n" ); document.write( "https://sooeet.com/math/system-of-linear-equations-solver.php \n" ); document.write( "
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