(a − 1/a)^2 − (a + 1/a)^2 =

(A) 4
(B) -4
(C) 2
(D) -2
(E) 2a

(B) -4

Step-by-step explanation:

so, do the multiplications and see :

(a - 1/a)² = a² - 2×a/a + 1/a² = a² - 2 + 1/a²

(a + 1/a)² = a² + 2×a/a + 1/a² = a² + 2 + 1/a²

now we need to subtract the second from the first :

(a² - 2 + 1/a²) - (a² + 2 + 1/a²) =

= a² - 2 + 1/a² - a² - 2 - 1/a² = -4

and that's it !

5x+40

5(x + 8)

7x - 49

7(x - 7)

18x + 9

9(2x + 1)

15x - 10

5(3x - 2)

step-by-step explanation:

for number one all you have to do is factor 5 out of 5x + 40

for number 2 factor 7 out of 7x - 49

for number three factor 9 out of 18x + 9

for number four factor 5 out of 15x - 10