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

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)

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

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

= √(4n²) +/- √(25)

= 2n +/- 5

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

the polynomial is a perfect square trinomial of the form a^2-2ab+b^2:

option a. true

step-by-step explanation:

9x^2-12x+4

comparing with the form a^2-2ab+b^2

1.) a^2=9x^2

solving for a: square root both sides of the equation:

sqrt(a^2)=sqrt(9x^2)

a=sqrt(9) sqrt(x^2)

a=3x

2.) b^2=4

solving for b: square root both sides of the equation:

sqrt(b^2)=sqrt(4)

b=2

to be a perfet square trinomial 2ab must be equal to 12x. let's check:

2ab = 2 (3x) (2)

2ab = 12x

correct

sina-sinb

cosb+cosa

tana-tanb

cos0+cos x pi/3

20tan

step-by-step explanation: