L LaylaSam May 2010 7 0 Australia Jun 19, 2010 #1 marnie can walk 1km/m faster the jon. She completes a 20km hike 1 hour before him. Write an equation and solve it to find there walking speeds. i cannot seem to solve this ahh (Headbang) plz help me (Speechless)

marnie can walk 1km/m faster the jon. She completes a 20km hike 1 hour before him. Write an equation and solve it to find there walking speeds. i cannot seem to solve this ahh (Headbang) plz help me (Speechless)

Grandad MHF Hall of Honor Dec 2008 2,570 1,416 South Coast of England Jun 19, 2010 #2 Hello LaylaSam LaylaSam said: marnie can walk 1km/m faster the jon. She completes a 20km hike 1 hour before him. Write an equation and solve it to find there walking speeds. i cannot seem to solve this ahh (Headbang) plz help me (Speechless) Click to expand... Suppose that Jon walks at \(\displaystyle x\) kph. Then Marnie walks at \(\displaystyle x+1\) kph. Using the formula \(\displaystyle \text{time} = \dfrac{\text{distance}}{\text{speed}}\)Marnie takes \(\displaystyle \frac{20}{x+1}\) hours, and Jon takes \(\displaystyle \frac{20}{x}\) hours. Since Jon takes \(\displaystyle 1\) hour more than Marnie, we get: \(\displaystyle \dfrac{20}{x}=\dfrac{20}{x+1}+1\)Now multiply both sides by \(\displaystyle x(x+1)\) to get rid of fractions: \(\displaystyle 20(x+1)=20x+x(x+1)\) \(\displaystyle \Rightarrow 20x+20=20x+x^2+x\) \(\displaystyle \Rightarrow x^2+x-20=0\) \(\displaystyle \Rightarrow (x+5)(x-4)=0\) \(\displaystyle \Rightarrow x = 4\), since \(\displaystyle x=-5\) is impossible. So Jon walks at 4 kph and Marnie at 5 kph. Grandad

Hello LaylaSam LaylaSam said: marnie can walk 1km/m faster the jon. She completes a 20km hike 1 hour before him. Write an equation and solve it to find there walking speeds. i cannot seem to solve this ahh (Headbang) plz help me (Speechless) Click to expand... Suppose that Jon walks at \(\displaystyle x\) kph. Then Marnie walks at \(\displaystyle x+1\) kph. Using the formula \(\displaystyle \text{time} = \dfrac{\text{distance}}{\text{speed}}\)Marnie takes \(\displaystyle \frac{20}{x+1}\) hours, and Jon takes \(\displaystyle \frac{20}{x}\) hours. Since Jon takes \(\displaystyle 1\) hour more than Marnie, we get: \(\displaystyle \dfrac{20}{x}=\dfrac{20}{x+1}+1\)Now multiply both sides by \(\displaystyle x(x+1)\) to get rid of fractions: \(\displaystyle 20(x+1)=20x+x(x+1)\) \(\displaystyle \Rightarrow 20x+20=20x+x^2+x\) \(\displaystyle \Rightarrow x^2+x-20=0\) \(\displaystyle \Rightarrow (x+5)(x-4)=0\) \(\displaystyle \Rightarrow x = 4\), since \(\displaystyle x=-5\) is impossible. So Jon walks at 4 kph and Marnie at 5 kph. Grandad