please find answer of 6 &7
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Step-by-step explanation:
6. a + 2b = 10
Cube both sides
(a+2b)³=10³
a³ + 8b³ + 6a²b + 12b²a = 1000
a³ + 8b³ + 6ab ( a+ 2b ) = 1000
a³ + 8b³ + 6(15)(10) = 1000
a³ + 8b³ + 900 = 1000
a³ + 8b³ = 100
7. a-3b = -6
Cube both sides
a³ - 27b³ - 9a²b + 27b²a = 36
a³ - 27b³ - 9ab(a-3b) = 36
a³ - 27b³ -9(-6)(-10) = 36
a³ - 27b³ = 576
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