Simplifying Expressions with Multiple Variables

Feedback: Not quite! To simplify $x \times x \times x$, we apply exponents. Since $x$ occurs 3 times in the multiplication, the expression becomes $x^3$.

Feedback: Not quite! When simplifying $4x + 3x$, we combine the like terms by adding their coefficients. $4 + 3 = 7$, so the simplified expression is $7x$.

Feedback: Not quite! $2a$ 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 for $a$. 

Feedback: Not quite! To simplify $2a + 3b + 5a - b$, collect the like terms: 1) Combine $2a$ and $5a$ to get $7a$. 2) Combine $3b$ and $-b$ to get $2b$. Thus, the simplified expression is $7a + 2b$.

Feedback: Not quite! $4ab^2$ and $3a^2b$ are not like terms because they have different variables and exponents. $4ab^2$ has $b^2$, whereas $3a^2b$ has $a^2$. 

Feedback: Not quite! First, we combine the like terms. When we add $7x^2$ and $-2x^2$, we get $5x^2$. Next, we combine $3xy$ and $-yx$, noting that $yx$ is the same as $xy$, so $3xy - xy$ equals $2xy$. Thus, the correct simplified expression is $5x^2 + 2xy$.