SOLUTION: please help, I am lost A car travels 150 mi at a certain speed, fi the speed has been 5mph faster, the trip would have been made in 1 hr. less time find the speed.

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Question 456643: please help, I am lost
A car travels 150 mi at a certain speed, fi the speed has been 5mph faster, the trip would have been made in 1 hr. less time find the speed.
Found 2 solutions by richwmiller, mananth:
Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website!
r*t=d
r*t=150
(r+5)*(t-1)=150
r=25 t=6
check
25*6=150
add 5 to speed and subtract one from time
30*5=150
ok

Answer by mananth(16946) (Show Source):
You can put this solution on YOUR website!
let the original speed = x
increased speed = x+5
t=d/r
original time - time with increased speed = 1
150/x -150/(x+5)=1
x(x+5) is the LCD
150(x+5)-150x= x(x+5)
150x+750-150x=x^2+5x
x^2+5x-750=0
Find the roots of the equation by quadratic formula

a= 1 ,b= 5 ,c= -750

b^2-4ac= 25 - 3000
b^2-4ac= 3025
= 55

x1=( -5 + 55 )/ 2
x1= 25
x2=( -5 -55 ) / 2
x2= -30
Ignore negative value
speed = 25 mph