factor:

a. 16b^2c^12-0.25

b. 81x^6y^2-0.36a^2

Step-by-step explanation:

a.   16b^2c^12-0.25 can be rewritten as follows because it is the difference of two squares:

(4bc^6 - .5)(4bc^6 + .5)

b.   81x^6y^2-0.36a^2

is the difference of two squares, just like (a) (above); its factors are:

(9x^3y - 0.6a)(9x^3y + 0.6a)

i = 2 / - 5

step-by-step explanation:

evaluation of ( 2 - 4 ) ( p + q ) when p = 2 and q = 5 i, by putting values of p and q,