4x - y = 1
3x + y = 13
Add the equations: 7x = 14 so that x = 2
and then, by the first equations, 4*2 - y= 1 so that y = 7
3x+5 = 2x+13 3x-2x = 13-5 x = 8
In the equation 3x plus 7 equals 13, x is equal to 2.
(x + 3)(x + 4y)
3+3x+7x=13 3x+7x=10 10x=10 x=1
You cannot add them. The 'y' in the 4xy means that you cannot add it to 3x, since the 'y' is an extra component that the 'x' does not have. You can add 3x to 3x, or 4y to 4y, but you cannot add terms which contain different variables to each other. (It's like trying to add apples and oranges, they're not the same thing).
x=4
3x+7=5x-13 ----> 3x-5x=-13-7 ----> -2x=-6 -----> x=3
2x+3y=13 3x-y=3 x=2
y = (13 - 3x)/2 and that cannot be simplified further.
3x - 7 = 5x + 13-2x = 20x = -10
If: 3x-7 = 5x+13 Then: x = -10
3x - 2 + 5 = 16 3x + 3 = 16 3x = 13 x = 13/3 ~ 4.333