Question

Without actually calculating the cubes, find the value of each of the following:
(1) (-12)3+(7)3 + (5)3
(ii) (28)3 +(-15)3 +(-13)3;​

Answer 1

Answer:

Try to do 2nd like this..

Step-by-step explanation:

Hope ot will help you.

Answer 2

QUESTION 1.

$\bold{(-12)³+(7)³ + (5)³}$

Consider

• a = -12
• b = 7
• c = 5

Then,

$\bold{a + b + c}$

$\bold{\leadsto -12 + 7 + 5}$

$\bold{\leadsto 0}$

By using

$a³ +b³ +c³=3abc$

If a+b+c = 0

So,

$\bold{(-12)³+(7)³ + (5)³}$

$\bold{\implies 3×(-12)×7×5}$

$\bold{\implies -1260}$

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QUESTION 2.

$\bold{(28)³+(-15)³ + (-13)³}$

Consider

• a = 28
• b = -15
• c = -13

Then,

$\bold{a + b + c}$

$\bold{\leadsto 28 -15 -13}$

$\bold{\leadsto 0}$

By using

$a³ +b³ +c³=3abc$

If a+b+c = 0

So,

$\bold{(28)³+(-15)³ + (-13)³}$

$\bold{\implies 3×28×-15×-13}$

$\bold{\implies 16380}$