Question

A body is weight by spring balance in 3 different medium . Spring balance shows 2kg in medium 1 , 3g in medium 2 , 4kg in medium 3 . Then which medium has greatest density?


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Answer 1

Answer:

2kg and medium 3 kg 9 is the density

Step-by-step explanation:

it is right answer follow

Answer 2

Given :-

a + b = 5

a² + b² = 11

To prove :-

a³ + b³ = 20

Solution :-

Using identity

(a + b)² = a² + b² + 2ab

Putting given values in it.

We get

(5)² = 11 + 2ab

25 = 11 + 2ab

2ab = 25 - 11

2ab = 14

ab = 14 / 2

ab = 7

Now,

Using another identity

a³ + b³ = (a + b)(a² + b² - ab)

R.H.S. = (a + b)(a² + b² - ab)

Putting given values in it.

We get

= (5)(11 - 7)

= 5 × 4

= 20

= L.H.S.

Hence, proved.

This kind of questions can be solved by using identities.

Some other identities are :-

(a - b)² = a² + b² - 2ab

(a - b)³ = a³ - b³ - 3a²b + 3ab²

(a + b)³ = a³ + b³ + 3a²b + 3ab²

a³ - b³ = (a - b)(a² + b² + ab)

a² - b² = (a + b)(a - b)

Upper one answer is refer to the attachment