Question

without actually calculating the cubes,find the value of 20cube + 10cube-30cube

Answer 1

7973000is the answer of 10*10*10+20*20*20-30*30*30

Answer 2

$Question \: = > ({20}^{3})+ ({10}^{3}) + (- {30}^{3})$

$If \: a + b + c = 0$

$Then \: {a}^{3} + {b}^{3} + {c}^{3} = 3abc$

$Value \: of \: = > a = 20, \: b = 10 ,\: c = - 30$

$=20 + 10 + ( - 30)$

$= 30 - 30$

$= 0$

$Hence \: \: {a}^{3} + {b}^{3} + {c}^{3} = 3abc$

$Substitute \: the \: values \: of \: a, \: b ,\: c$

$({20}^{3})+ ({10}^{3}) + (- {30}^{3}) = 3(20)(10)( - 30)$

$= - 18000$

$Therefore \: the \: answer \: = \: -18000$