Which is an example of the associative property? O x+ 5 - 5 + x
O (x + 3) + 7 = x + (3 + 7)
O 3
3. (x + 5) = 3 . x + 15
If x= a, and a = 7, then x = 7.

people went from manufacturing one object at a time by hand to manufacturing many objects in factories

x^2 + 81

we can factor this using difference of square binomials.

rewrite the equation:

x^2 - (-81)

factor:

(a^2 - b^2) = (√a^2 + √b^2)(√a^2 - √b^2)

(x^2 - (-81) = (x + √-81)(x - √-81)

we can remove the - from under the radical by multiplying it by i.

(x^2 - (-81) = (x + i√81)(x - i√81)

(x^2 - (-81) = (x + 9i)(x - 9i)

we can check our answer by using foil:

x^2 - 9ix + 9ix - 81i^2

x^2 - 81^2

i^2 = -1

x^2 + 81