Step-by-step explanation:
To find : Write a variable expression the algebraic expression ?
Solution :
A variable is defined as the symbol for a number we don't know yet.
It is usually a letter like x or y.
1) [tex]3x+7[/tex]
The variable in the expression is unknown value i.e. x.
2) [tex]x-9[/tex]
The variable in the expression is unknown value i.e. x.
3) [tex]x^2-2x[/tex]
The variable in the expression is unknown value i.e. x.
4) [tex]\frac{a}{2b}[/tex]
The variable in the expression is unknown value i.e. 'a' and 'b'.
