If-one-side-of-a-square-reduces-by-10-and-the-adjacent-side-increases-by-30-Using-the-application-of-differentiationfind-the-change-in-the-area-of-the-square-

Question Number 26774 by NECx last updated on 29/Dec/17

I f o n e s i d e o f a s q u a r e r e d u c e s b y

10 % a n d t h e a d j a c e n t s i d e i n c r e a s e s

b y 30 % . U s i n g t h e a p p l i c a t i o n o f

d i f f e r e n t i a t i o n f i n d t h e % c h a n g e

i n t h e a r e a o f t h e s q u a r e .

Commented by NECx last updated on 30/Dec/17

p l e a s e h e l p

Commented by prakash jain last updated on 30/Dec/17

A = l b

\frac{d A}{d t} = b \frac{d l}{d t} + l \frac{d b}{d t}

i n i t i a l l y l = b a n d A = b^{2}

\frac{d b}{d t} = - . 1 b

\frac{d l}{d t} = + . 3 l

\frac{d A}{d t} = b \times . 3 l - l \times . 1 b = . 2 l b = . 2 A

Area will increase by 20 %

Commented by NECx last updated on 31/Dec/17

w o w \dots . t h i s i s w o n d e r f u l

Commented by prakash jain last updated on 31/Dec/17

Since the question asked for use

of derivate i answered as in comment .

I assumed 30 % and 10 % question

as rate of change .

Commented by NECx last updated on 02/Jan/18

i t s r e a l l y n i c e \dots . I^{'} v e a l w a y s

t j o u g h t o f i t b u t h a v e n e v e r k n o w n

h o w t o a p p l y i t u n t i l n o w .

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