please give the answer to this ques?

Asked by ishita605 | 8th Oct, 2016, 04:48: PM

Expert Answer:

Given space that space straight x space equals space straight y space equals straight z.
We space will space substitute space straight x space equals space straight y space equals straight z space in space all space the space options space and space see space whether space we space get space LHS space equals space RHS.

left parenthesis straight i right parenthesis space LHS space equals space straight x cubed space plus space straight y cubed space plus space straight z cubed space equals space space straight x cubed space plus space straight x cubed space plus space straight x cubed space equals space 3 straight x cubed space space
RHS space equals space 3 xyz space equals space space 3 xxx space equals space 3 straight x cubed space space
therefore LHS space equals space RHS

left parenthesis ii right parenthesis LHS space equals space straight x cubed space plus space straight y squared straight z space plus space yz squared space equals space space straight x cubed space plus space straight x cubed space plus space straight x cubed space equals space 3 straight x cubed space space
RHS space equals space 3 xyz space equals space space 3 xxx space equals space 3 straight x cubed space space
therefore LHS space equals space RHS

left parenthesis iii right parenthesis LHS space equals space straight x cubed space plus space straight y squared straight z space plus space straight z squared straight x space equals space space straight x cubed space plus space straight x cubed space plus space straight x cubed space equals space 3 straight x cubed space space
RHS space equals space 3 xyz space equals space space 3 xxx space equals space 3 straight x cubed space space
therefore LHS space equals space RHS

left parenthesis iv right parenthesis LHS space equals open parentheses space straight x space plus space straight y space plus space straight z close parentheses cubed space space equals space open parentheses space straight x space plus space straight x space plus space straight x close parentheses cubed space space equals space open parentheses 3 straight x close parentheses cubed space space equals 27 straight x cubed
RHS space equals space 27 xyz space equals space space 27 xxx space equals space 27 straight x cubed space space
therefore LHS space equals space RHS

Option space left parenthesis straight D right parenthesis space is space correct

Answered by Vijaykumar Wani | 10th Oct, 2016, 10:07: AM

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