Archive
24th of March 2017
Mathematics
Q:

If x+y+z =9, then find the value of (3-x)3 + (3-y)3 + (3-z)3 -3(3-x) (3-y) (3-z)?

Nisha_vini29 - CBSE - Class IX

Friday, March 24, 2017 at 17:51:PM

A:

begin mathsize 16px style left parenthesis 3 minus straight x right parenthesis cubed space plus space left parenthesis 3 minus straight y right parenthesis cubed space plus space left parenthesis 3 minus straight z right parenthesis cubed space minus 3 left parenthesis 3 minus straight x right parenthesis space left parenthesis 3 minus straight y right parenthesis space left parenthesis 3 minus straight z right parenthesis
Here comma space take space straight a equals 3 minus straight x comma space straight b equals 3 minus straight y comma space straight c equals 3 minus straight z
using space formula space for space straight a cubed plus straight b cubed plus straight c cubed minus 3 abc equals open parentheses straight a plus straight b plus straight c close parentheses open parentheses straight a squared plus straight b squared plus straight c squared minus ab minus bc minus ca close parentheses
But comma
straight a plus straight b plus straight c space you space will space get space it space as space 0 space using space straight x plus straight y plus straight z equals 9.
Answer space is space 0.
end style

Friday, March 24, 2017 at 18:23:PM