Without actually calculating the cubes find the value of
a)48^3- 30^3 – 18^3
Answers
Answered by
0
Answer:
so,110592-27000-5832
110592-32832
=77760
Answered by
7
Answer:
Step-by-step explanation:
48³ - 30³ - 18³
= 48³ - 18³ - 30³
= (48³ - 18³) - 30³
= (48 - 18)(48² + 48×18 + 18²) - 30³ …… As a³ - b³ = (a - b)(a² + ab + b²)
= 30 × (48² + 48×18 + 18²) - 30³
= 30 × [(48² + 48×18 + 18²) - 30²]
= 30 × [(48² - 30²) + 48×18 + 18²]
= 30 × [(48 + 30)(48 - 30) + 48×18 + 18²] ……
As a² - b² = (a + b)(a - b)
= 30 × [78 × 18 + 48×18 + 18²]
= 30 × 18 × 144
= 77760
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