Q. 21

# If the list price

Answer :

To find: Original price of toy.

Method Used:

To solve the quadratic equation by factorisation method, follow the steps:

1) Multiply the coefficient of x2 and constant term.

2) factorise the result obtained in step 1.

3) Now choose the pair of factors in such a way that after adding or subtracting(splitting) them

You get coefficient of x.

Explanation:

Let the original price of the toy be ‘a’.

Given, when the list price of a toy is reduced by Rs. 2, a person can buy 2 toys more for Rs. 360.

Number of toys he can buy at original price for Number of toys he can buy at reduced price According to the question,  360a = (a – 2) (360 + 2a)

360a = 360a + 2a2 – 720 – 4a

a2 – 2a – 360 = 0

a2 – 20a + 18a – 360 = 0

a (a – 20) + 18(a – 20) = 0

(a + 18) (a – 20) = 0

a = -18 and a = 20

As price cannot be negative.

a = Rs. 20

Hence price of toy is Rs 20.

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