Question

How to write a quadratic equation from word problem

Answer 1

First u should understand the problem. And there u go .... now u can jot down your equation.....

Answer 2

Writing a quadratic equations can be tricky at times, but mostly is easy.
Just read the question thoroughly line by line and break it into parts.If you are in class 10 or lower then mostly the questions will have 2 equations.
Break the questions and make equations for each part, if you don’t break the question in parts it would be difficult for you !

General form - Ax^2 + bx + y = 0
You need make the equation in this form.

I’m giving two examples for your better understanding -

Example 1 - ( Easy )

The area of a rectangular plot is 528 m2. The length of the plot (in metres) is one more than twice its breadth. We need to find the length and breadth of the plot.
( NCERT CLASS X )

Solution -
Let the breadth of the plot be x m.
Hence, the length of the plot is (2x + 1) m.
Area of a rectangle = Length × Breadth
∴ 528 = x (2x + 1)
2x^2 + x - 528 = 0

You can solve it further by mid term split or quadratic formula


Example 2 - ( Tough )

A train travels a distance of 480 km at a uniform speed. If the speed had been 8 km/h less, then it would have taken 3 hours more to cover the same distance. We need to find the speed of the train.
( NCERT CLASS X )


Solution -

Let the speed of train be x km/h.
Time taken to travel 480 km = 480/x hours
In second condition, let the speed of train = (x-8) km/h
It is also given that the train will take 3 hours to cover the same distance.

Therefore, time taken to travel 480 km = ( 480/x + 3 ) hrs

Speed × Time = Distance
(X-8) (480/x + 3) = 480
480 + 3x - 3840/x = 24
3x^2 - 24x - 3840 = 0
X^2 - 8x - 1280 = 0


Hope it helped !
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