2(xy)
y=2x
If the expression is (x - y)2, the solution is (7 - -2)2 = (7+2)2 = 92 = 81. If the expression is x - y2, the solution is 7 - (-2)2 = 7 - 4 = 3.
A mathematical expression in its' most simplistic form, merely assigns a value to a variable. Don't confuse an expression with an equation. An equation requires a solution. An expression cannot be "solved". It only allows you to determine the value of a variable. This is the expression in words "x is equal to 3" (X is the variable which is equal to the constant number 3) This is the expression in numbers "x=3" The expression in words "y is equal to 6" (Y is the variable which is equal to the constant number 6) The expression in numbers is "y=6" I hope you understand now.
y - x - 3 is an expression, not an equation nor an inequality. It cannot, therefore, have a solution.
7
The expression for the number ( y ) being 6 less than twice a number ( x ) can be written as ( y = 2x - 6 ). This indicates that you first double the value of ( x ) and then subtract 6 to obtain ( y ).
y - 5x
x times y or, symbolically, either x*y or simply xy (where context allows, also X x Y)
yz - x
Twice the sum of 'x' and 'y' . . . 2(x+y) The sum of twice 'x' and 'y' . . . (2x+y)
The expression "y - 2x^3" represents a mathematical expression where "y" is a variable and "2x^3" is a term involving another variable "x." It indicates that you subtract twice the cube of "x" from "y." Without additional context or values for "y" and "x," this expression cannot be further simplified or evaluated.
x / (2y - 7)
3(2y)(x)6xy
2(x+y) is twice the sum of x and y, and 2x+y is the sum of twice x and y
0.5*xy
This phrase might be represented by the mathematical expression Y + (-5x). Because there is no additional information, you cannot determine what either Y or x is.
4(x+y)