Question

14. By what amount area of a rectangle is to be increased, if its length and breadth
are increased by 30 units and 40 units respectively.
Hint : Answer will be in terms of l and b, where l and b are length and breadth of the
rectangle).​

Answer 1

Let L = initial length

Let W = initial breadth

Let I = increase in area…Then…

I = (L+30)(W+40) - LW

I = LW +30W +40L +1200 - LW

I = 30W +40L +1200

Answer 2

Answer:

Area is increased by 40l+30b+1200

Step-by-step explanation:

Let the length of the rectangle = l

Let the breadth of the rectangle = b

Area of the rectangle = A1 = l×b

Now,

length is increased by 30 units

So the new length = l+30

breadth is increased by 40 units

So the new breadth = b+40

So new Area = A2= (l+30)(b+40) =

(l×b)+40l+30b+1200

A1 + 40l+30b+1200