You can
put this solution on YOUR website!first part 48 miles
second part 5 miles
speed in first part x mph
speed second part x -5 mph
Total rowing time 3 hours
Time first part 48 / x
Time second part 5 / ( x -5 )
Time first part + time second part = 3 hours
48 / x + 5 /(x -5 ) = 3
LCD = ( x + 0 )* (x -5 )
multiply the equation by the LCD
we get
48 * (x -5 )+ 5 x = 3
48 x -240 + 5 x = 3 X^2
68 x -240 = 3 X^2
3 X^2 -68 x 240 = 0
3 X^2+ -68 x+ 240 =
/ 3
1 X^2 -22.67 x 80 =
Find the roots of the equation by quadratic formula
a= 1 b= -22.67 c= 80
b^2-4ac= 513.78 - -320
b^2-4ac= 193.78
= 13.92
x1=( 22.67 + 13.92 )/ 2
x1= 18.29 18 2/7
x2=( 22.67 -13.92 ) / 2
x2= 4.37 4 3/8
Ignore negative value
x = 18.29 mph speed & 5 less in the second part
CHECK
Time first part + Time second part
2.62 + 0.38 = 3
