Question 1107231
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<pre>
                 SPEED       TIME            DISTANCE

A to B            r          133/r            133

B to C           r+14        168/(r+14)       168

DIFFERENCE                    7/60
</pre>


{{{highlight_green(168/(r+14)-133/r=7/60)}}}
Simplify and solve this equation.

-

{{{24/(r+14)-19/r=1/60}}}

-
{{{24r-19(r+14)=(r^2+14r)/60}}}


{{{24*60r-19*60(r+14)=r^2+14r}}}

{{{1440r-1140r-15960=r^2+14r}}}

{{{300r-15960=r^2+14r}}}

{{{r^2-286r+15960=0}}}


discriminant,...  17956
discriminant, {{{17956=134^2}}}
<pre>(286^2-4*15960=81796-63840=17956)</pre>


{{{r=(286+- 134)/2}}}



first part of trip:    {{{system(highlight(r=76), OR, highlight(r=210))}}}