Answer: 6i) 6a² - 2ab
6ii) -2b³
6iii) b³ + 7b² - 49b
<u>Step-by-step explanation:</u>
6i) (a + b)(5a - 3b) + (a - 3b)(a - b)
= 5a² - 3ab + 5ab - 3b² + a² - ab - 3ab + 3b²
= 5a² + 2ab - 3b² + a² - 4ab + 3b²
= 6a² - 2ab
6ii) (a - b)(a² + b² + ab) - (a + b)(a² + b² - ab)
= a³ + ab² + a²b - ab² - a²b - b³ - (a³ + ab² - a²b -ab² + a²b + b³)
= a³ - b³ - (a³ + b³)
= a³ - b³ - a³ - b³
= -2b³
6iii) (b² - 49)(b + 7) + 343
= b³ + 7b² - 49b - 343 + 343
= b³ + 7b² - 49b
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Please post #7 on a different question.
Step 1 : Find the difference [ 891 - 876 = 15 ]
Step 2 : Determine the percentage
Answer: 15% from last year
:)
We can always split a regular polygon with 
sides into triangles, whose base is the side of the polygon and whose height is the apothem of the polygon. So, the sum of the areas of all these triangles is
where is the number of sides, 
is the side length, and 
is the apothem length.
So, you just need to plug you values in: in your case, you have 
So, the formula becomes
