Wanni cycled 6 km from her house to the school at a uniform speed, v km/h. If she increased her speed
by 2 km/h, she would arrive at the school 4 minutes earlier. Form a quadratic equation in term of v.​

Respuesta :

Answer:

The quadratic equation in terms of v is   v² + 2 v + 180 = 0

Step-by-step explanation:

Given as :

The distance between house to the school = d = 6 km

The uniform speed = v km/h

So, Time = [tex]\dfrac{\textrm Distance}{\textrm speed}[/tex]

or, t = [tex]\dfrac{\textrm d}{\textrm v}[/tex]

Or, t = [tex]\dfrac{\textrm 6}{\textrm v}[/tex]

Now, Again

The speed is increase by 2 km/h

i.e speed = (v + 2) km/h

So, Time taken = t' = (t - [tex]\dfrac{4}{60}[/tex])hours

i.e t' =  (t - [tex]\dfrac{1}{15}[/tex])hours

Now, Time = [tex]\dfrac{\textrm Distance}{\textrm speed}[/tex]

So, (t - [tex]\dfrac{1}{15}[/tex]) = [tex]\dfrac{\textrm d}{\textrm v}[/tex]

Or,  (t - [tex]\dfrac{1}{15}[/tex]) = [tex]\dfrac{\textrm 6}{\textrm (v + 2)}[/tex]

Or , [tex]\dfrac{\textrm 6}{\textrm v}[/tex] -  [tex]\dfrac{1}{15}[/tex] = [tex]\dfrac{\textrm 6}{\textrm (v + 2)}[/tex]

Or , [tex]\dfrac{\textrm 90 - v}{\textrm 15 v}[/tex] = [tex]\dfrac{\textrm 6}{\textrm v + 2}[/tex]

Or, (90 - v) × (v + 2) = 6 × 15 v

Or, 90 v - 180 - v² - 2 v = 90 v

Or,  v² + 2 v + 180 = 90 v - 90 v

Or,  v² + 2 v + 180 = 0

So, The quadratic equation in terms of v

v² + 2 v + 180 = 0

Hence The quadratic equation in terms of v is   v² + 2 v + 180 = 0   Answer