Speed of car

The car went to a city that was 240 km away. If his speed increased by 8 km/h, it would reach the finish one hour earlier. Determine its original speed.

Result

v =  40 km/h

Solution:

s=vt  240=vt 240=(v+8)(t1)  240=(v+8)(240/v1)   240 v=(v+8) (240v) v2+8v1920=0  a=1;b=8;c=1920 D=b24ac=8241(1920)=7744 D>0  v1,2=b±D2a=8±77442 v1,2=8±882 v1,2=4±44 v1=40 v2=48   Factored form of the equation:  (v40)(v+48)=0 v>0  v=v1=40 km/hs=vt \ \\ \ \\ 240=vt \ \\ 240=(v+8)(t-1) \ \\ \ \\ 240=(v+8)(240/v-1) \ \\ \ \\ \ \\ 240 \cdot \ v=(v+8) \cdot \ (240-v) \ \\ v^2 +8v -1920=0 \ \\ \ \\ a=1; b=8; c=-1920 \ \\ D=b^2 - 4ac=8^2 - 4\cdot 1 \cdot (-1920)=7744 \ \\ D>0 \ \\ \ \\ v_{1,2}=\dfrac{ -b \pm \sqrt{ D } }{ 2a }=\dfrac{ -8 \pm \sqrt{ 7744 } }{ 2 } \ \\ v_{1,2}=\dfrac{ -8 \pm 88 }{ 2 } \ \\ v_{1,2}=-4 \pm 44 \ \\ v_{1}=40 \ \\ v_{2}=-48 \ \\ \ \\ \text{ Factored form of the equation: } \ \\ (v -40) (v +48)=0 \ \\ v>0 \ \\ \ \\ v=v_{ 1 }=40 \ \text{km/h}

Checkout calculation with our calculator of quadratic equations.




Our examples were largely sent or created by pupils and students themselves. Therefore, we would be pleased if you could send us any errors you found, spelling mistakes, or rephasing the example. Thank you!





Leave us a comment of this math problem and its solution (i.e. if it is still somewhat unclear...):

Showing 0 comments:
1st comment
Be the first to comment!
avatar




Tips to related online calculators
Looking for help with calculating roots of a quadratic equation?
Do you have a linear equation or system of equations and looking for its solution? Or do you have quadratic equation?
Do you want to convert velocity (speed) units?
Do you want to convert time units like minutes to seconds?

Next similar math problems:

  1. Two planes
    aircraft2 Two planes flying from airports A and B, 420 km distant against each other. Plane from A took off 15 minutes later and flies at an average speed of 40 km/h higher than the plane from B. Determine the average speed of this two aircraft if you know that i
  2. The cruise ship
    ship_3 The cruise ship has a speed of 12 km / h at a calm surface. When we sail 45 km along the river and 45 km back, it took us exactly 8 hours. Which (constant) speed of flow of the river?
  3. Wind drift
    airplane The plane flies at 860 km/h, passing distance 3000 kilometers with the wind and once again against the wind for 6 h 59 min. What is the wind speed?
  4. Age problems
    time_1 A) Alex is 3 times as old as he was 2 years ago. How old is he now? b) Casey was twice as old as his sister 3 years ago. Now he is 5 years older than his sister. How old is Casey? c) Jessica is 4 years younger than Jennifer now. In 10 years, Jessica wi
  5. The product
    eq222 The product of a number plus that number and its inverse is two and one-half. What is the inverse of this number
  6. Stones 3
    stones Simiyu and Nasike each collected a number of stones in an arithmetic lesson. If Simiyu gave Nasike 5 stones, Nasike would have twice as many stones as Simiyu. If initially, Simiyu had five stones less than Nasike how many stones did each have?
  7. Quadratic equation
    kvadrat_2 Find the roots of the quadratic equation: 3x2-4x + (-4) = 0.
  8. Equation 23
    reciprocal_1 Find value of unknown x in equation: x+3/x+1=5 (problem finding x)
  9. Algebra
    parabol_3 X+y=5, find xy (find the product of x and y if x+y = 5)
  10. Elimination method
    rovnice_1 Solve system of linear equations by elimination method: 5/2x + 3/5y= 4/15 1/2x + 2/5y= 2/15
  11. Theorem prove
    thales_1 We want to prove the sentence: If the natural number n is divisible by six, then n is divisible by three. From what assumption we started?
  12. Discriminant
    Quadratic_equation_discriminant Determine the discriminant of the equation: ?
  13. Square root 2
    parabola_2 If the square root of 3m2 +22 and -x = 0, and x=7, what is m?
  14. Pooja
    clocks_14 Pooja and Deepa age is 4:5, 4 years back it was 8:11. What is the age of Pooja now?
  15. Father 7
    family_8 Father is 6 times older than his son. After 4 years, the father will only be 4 times older. What are their present ages?
  16. Three workshops
    workers_24 There are 2743 people working in three workshops. In the second workshop works 140 people more than in the first and in third works 4.2 times more than the second one. How many people work in each workshop?
  17. Lee is
    clock-night-schr_15 Lee is 8 years more than twice Park's age, 4 years ago, Lee was three times as old. How old was Lee 4 years ago?