posted by Kelsie .
Factor each polynomial comletely.
4x^2-18 = (2x + sqrt18)(2x - sqrt18)
= 4[x + (3/2)sqrt2][x - (3/2)sqrt2]
On the second one, factor out the 7 and recognize that 121 = 11^2. Ypu will have the difference of two squares.
The third one requires imaginary factors.
4x^2 + 18 = 4(x^2 + 2*9/4)
= 4[x + i(3/2)sqrt2][ x - i(3/2)sqrt2]