math
posted by Hannah on .
sovle: (3x  2y)^2
The answer is 9x^2 + 4y^2  12xy but I do not know how to get the 12xy part.
20  4/5x is greater that or equal to 16, then:
The answer is x is less thatn or equal to 5 but again I do not know how to get this.

(3x  2y)^2 = (3x2y)(3x2y)
You could use FOIL
(3x)(3x)+(3x)(2y)+(2y)(3x)+(2y)(2y)
= 9x^2 12xy +4y^2
or use the distributive property of multipication directly
3x(3x2y)  2y(3x2y)
=9 x^2 6xy 6xy + 4y^2
= 9x^2  12 xy + 4y^2 
20  4/5x >/= 16
If that is what you mean then
100 x  4 >/= 80 x
20 x  4 >/= 0
20 x >/= 4
x >/= 1/5
or if you mean
20  (4/5)x >/= 16
20  16 >/= (4/5) x
4 >/= (4/5) x
5 >/= x