Question

5. Solve the following questions. (Any one)
i. Construct a word problem on quadratic equation such that one of its answers is 20 (years,
rupees, centimetres, etc.). Also solve it.​

Answer 1

The original length of square was 20 cm.

Step-by-step explanation:

Que:

A carpenter bought a square shape wooden piece. He cuts this wooden piece in such a way that its length is decreased by 5 cm and width is decreased by 3 cm. If its area is 255 sq cm. Then what was its length originally?

Solution :

let's assume the length of square shape wooden piece = x cm

But, since its length and width is decreased by 5 cm  and 3 cm respectively. So, it becomes a rectangle.

The area of this rectangle =$(x-5)\times (x-3)$

$255 = (x-5) (x-3)$

$255 = x^2-5x-3x+15$

$240 = x^2-8x$

$x^2-8x-240=0$

$x^2-20x+12x-240=0$

$x(x-20)+12(x-20)=0$

$(x-20)(x+12)=0$

$x= -12 , 20$

since, length can not be negative, so the original length was 20 cm.