Question

Find the value of 1/27rcube - s cube +125t cube + 5rst where s=r/3+5t

Answer 1

s = (r/3) + (5t)

Cubing on both sides,

(s)3 = (r/3 + 5t)3

⇒ s3 = r3/27 + 125 t3 + 3 (r/3)(5t)(r/3 + 5t)

⇒ s3 = r3/27 + 125 t3 + (5rt)(r/3 + 5t)

⇒ s3 = r3/27 + 125 t3 + 5 rst

⇒ r3/27 - s3 + 125 t3 + 5 rst = 0

Therefore, the value of 1/27 r3 - s3 + 125 t3 + 5 rst = 0.

Answer 2

Answer:

0

Step-by-step explanation:

s = (r/3) + (5t)

Cubing on both sides,

(s)3 = (r/3 + 5t)3

⇒ s3 = r3/27 + 125 t3 + 3 (r/3)(5t)(r/3 + 5t)

⇒ s3 = r3/27 + 125 t3 + (5rt)(r/3 + 5t)

⇒ s3 = r3/27 + 125 t3 + 5 rst

⇒ r3/27 - s3 + 125 t3 + 5 rst = 0

Therefore, the value of 1/27 r3 - s3 + 125 t3 + 5 rst = 0.

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