## amin_alam_siddiqui 3 years ago i want to ask the cube of 3x-1/3y plzz answer this algebraic question with steps

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1. punnus

There is an algebraic identity for such question. You want to cube of (3x-1/3y). Such type is identified by (a-b)^3. i.e $a ^{3}-b ^{3}-3ab(a-b)$ Now put the value of a=3x and b=1/3y and solve it.

2. amin_alam_siddiqui

ACTUALLY THATS WHAT I CANNOT DO ALTHOUGH I KNOW THE IDENTITY PLZZ HELP ME WITH THE STEPS

3. punnus

where do you get stuck

4. amin_alam_siddiqui

FROM THE FIRST STEP

5. punnus

see since a=3x and b=1/3y, first find the cube of both a and b i.e a^3=27x^3 and b^3=1/27y^3. Do you get it...

6. amin_alam_siddiqui

WHAT DOES ^ THIS SIGN MEANS

7. punnus

raise to power of

8. amin_alam_siddiqui

ok yah am getting it then

9. punnus

now calculate the value of 3a^2b i.e $3\times(3x)^{2}\times(1/3y)$ Which is equal to $9x ^{2}/y$

10. punnus

are you there