If a + 2b = 5; then show that : a 3 + 8b 3 + 30ab = 125.

Given, ⇒ a + 2b = 5 Cubing both sides we get : ⇒ (a + 2b) 3 = 5 3 ⇒ a 3 + (2b) 3 + 3 × a × 2b (a + 2b) = 125 ⇒ a 3 + 8b 3 + 6ab(a + 2b) = 125 ⇒ a 3 + 8b 3 + 6ab × 5 = 125 ⇒ a 3 + 8b 3 + 30ab = 125. Hence, proved that a 3 + 8b 3 + 30ab = 125.

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Mathematics

If a + 2b = 5; then show that :
a³ + 8b³ + 30ab = 125.

Expansions

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Answer

Given,

⇒ a + 2b = 5

Cubing both sides we get :

⇒ (a + 2b)³ = 5³

⇒ a³ + (2b)³ + 3 × a × 2b (a + 2b) = 125

⇒ a³ + 8b³ + 6ab(a + 2b) = 125

⇒ a³ + 8b³ + 6ab × 5 = 125

⇒ a³ + 8b³ + 30ab = 125.

Hence, proved that a³ + 8b³ + 30ab = 125.

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Mathematics

If a + 2b = 5; then show that :
a³ + 8b³ + 30ab = 125.

Expansions

Answer

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If a + 2b = 5; then show that :a3 + 8b3 + 30ab = 125.

Expansions

Answer

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