Find the value of 58 cube -24 cube - 34 cube
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4
58×58×58=195112
24×24×24=13824
34×34×34=39304
195112-13824-39304=141984
24×24×24=13824
34×34×34=39304
195112-13824-39304=141984
Answered by
2
For such questions, one should use algebra and avoid large number multiplications. The calculator is not supposed to be used.
use a³ - b³ = (a - b) (a² + ab + b²)
58³ - 24³ - 34³
= (58 - 24)(58² + 58 * 24 + 24²) - 34³
= 34 * [ 58² + 24 (58 + 24) - 34² ]
= 34 * [ 58² - 34² + 24 * 82 ]
= 34 * [ (58+34)(58 - 34) + 24 * 82 ]
= 34 * [ 92 * 24 + 24 * 82 ]
= 34 * 24 * 174
= 17 * 12 * 4 * (175 -1)
= 17 * 12 * (700 - 4)
= 17 * 6 * (1400 - 8)
= 102 * 1400 - 8 * 102
= 142, 800 - 816
= 141, 984
use a³ - b³ = (a - b) (a² + ab + b²)
58³ - 24³ - 34³
= (58 - 24)(58² + 58 * 24 + 24²) - 34³
= 34 * [ 58² + 24 (58 + 24) - 34² ]
= 34 * [ 58² - 34² + 24 * 82 ]
= 34 * [ (58+34)(58 - 34) + 24 * 82 ]
= 34 * [ 92 * 24 + 24 * 82 ]
= 34 * 24 * 174
= 17 * 12 * 4 * (175 -1)
= 17 * 12 * (700 - 4)
= 17 * 6 * (1400 - 8)
= 102 * 1400 - 8 * 102
= 142, 800 - 816
= 141, 984
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