Question

Упростите выражение 13(3а-6) - 1 2(2в-4),   если а=1 1/2,   в=2/5

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Answer 1

13(3a - 6) - 12(2b - 4) =
= 39a - 78 - 24b + 48 =
= 39a - 24b - 30 =
= 3(13a - 8b) - 30 =

при a = 1 1/2,   b = 2/5

= 3 • (13 • 1 1/2 - 8 • 2/5) - 30 =
= 3 • (13 • 3/2 - 16/5) - 30 =
= 3 • (39/2 - 16/5) - 30 =
= 3 • (195/10 - 32/10) - 30 =
= 3 • 163/10 - 30 =
= 489/10 - 300/10 =
= 189/10 = 18,9

Ответ: 18,9