Question

Factor each completely 5n^2-8n-21 6r^2+53r-79 4n^2-25

Answer 1

1- (5n + 7)(n - 3)

3-(2n + 5)(2n - 5)

not really sure what #2 is

Answer 2

5n² - 8n - 21    →    (5)(- 21) = -105    (find 2 numbers whose product is 105 and sum is -8)

= 5n² - 15n  + 7n - 21

= 5n(n - 3)  + 7(n - 3)

= (5n + 7)(n - 3)

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6n² + 53n - 79 → (6)( -79) = -474 (find 2 numbers whose product is -474 and sum is 53)  DOES NOT EXIST! only factors are: (1, 474) (2, 237) (3, 158) (6, 79)

= Prime

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4n² - 25   (this is the difference of two squares)

= √(4n²) +/- √(25)

= 2n +/- 5

= (2n + 5)(2n - 5)