Simplifying Expressions with Multiple Variables

To simplify $x\times x\times x$, we apply exponents. Since $x$ occurs 3 times in the multiplication, the expression becomes $x^3$.

When simplifying $4x+3x$, we combine like terms by adding their coefficients. $4+3=7$, so the simplified expression is $7x$.

$2a$ and $a^2$ are not like terms because they have different exponents. $2a$ has an exponent of 1 for $a$, whereas $a^2$ has an exponent of 2.

To simplify $2a+3b+5a-b$, collect like terms. Combine $2a$ and $5a$ to get $7a$. Combine $3b$ and $-b$ to get $2b$. Thus, the simplified expression is $7a+2b$.

$4a{b}^2$ and $3a^{2}b$ are not like terms because they have different variables and exponents. $4a{b}^2$ has $b^2$, whereas $3a^{2}b$ has $a^2$.

First, combine like terms. $7x^2-2x^2=5x^2$. Next, note that $yx$ is the same as $xy$, so $3xy-xy=2xy$. Thus, the simplified expression is $5x^2+2xy$.