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5. Solve: (2n – 5)^2= 81

User Illidan
by
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1 Answer

2 votes

Answer:

(n -7)(4n + 8) = 0

Explanation:

(a -b)² = a² - 2ab + b²

(2n - 5)² = 81

(2n)² - 2*2n*5 + 5² = 81

4n² - 20n + 25 = 81

4n² - 20n + 25 - 81 = 0

4n² - 20n - 56 = 0

4n² - 28n + 8n - 8*7 = 0

4n*(n -7) + 8*(n - 7) = 0

(n -7)(4n + 8) = 0

User David Fregoli
by
5.1k points