Math
posted by kelly .
Solve the system of equations
3xy=11
5x+y=12
2.
Perform the indicated operation and simplify (5/(x2)+(4(x^22x)
3.simpify and write with only positive exponents (7x^3y^2)/(x^4y^9)^3
4.
find the solution of the inequality
2x11 is less than or equal to 4(5x3)
5. the length of a recangle is 5 feet less than twice the width. the area is 25 square feet. using w as the variable. write an equation that can be used to calculate the width.
(2w^25)

Any help would be appreciated. This is for my study guide in order to do well on my test. Someone please help.

#1
From the first, y=3x11
Plug that into the second:
5x+3x11 = 12
2x = 23
x = 23/2
y = 91/2
Or, you can just add the equations to eliminate the y terms:
5x = 23
...
#2 Your parentheses are unbalanced. If you mean
5/(x2) + 4/(x^22x)
5/(x2) + 4/(x(x2))
5x/(x(x2)) + 4/(x(x2))
(5x+4)/(x(x2))
(5x+4)/(x^22x)
#3
(7x^3y^2)/(x^4y^9)^3
(x^4y^9)^3 = x^12 y^27
Since you're dividing by that, you have
(7x^3y^2)*(x^12 y^27)
7x^9 y^25
7y^25/x^9 
#4.
2x11 <= 4(5x3)
2x11 <= 20x + 12
22x <= 23
x <= 23/22
#5.
length is 2w5
area is 25, so
w(2w5) = 25
2w^25w = 25
2w^2  5w  25 = 0
(2w+5)(w5) = 0
w=5 (5/2 is not a usable width)
the rectangle is a square 5x5