CBSE Notes, Lectures

CBSE - Mathematics - Quadratic Equations

Quadratic Equations

NCERT Exercise Exercise 4.2

A cottage industry produces a certain number of toys in a day. The cost of production of each toy (in rupees) was found to be 55 minus the number of toys produced in a day. On a particular day, the total cost of production was Rs 750. Find out the number of toys produced on that day.

Let the number of toys produced be x.
∴ Cost of production of each toy = Rs (55 - x)
It is given that, total production of the toys = Rs 750

∴ x(55 - x) = 750

⇒ x2 – 55x + 750 = 0

⇒ x2 – 25x - 30x + 750 = 0

 x(x - 25) -30(x - 25) = 0

⇒ (x - 25)(x - 30) = 0

Either, x -25 = 0 or x - 30 = 0
⇒ x = 25 or x = 30
Hence, the number of toys will be either 25 or 30.

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