4. Collect like terms: a) 3x+4x b) 8x-3x+2-5 c) 2y+3x+4y-x+10 d) 3x^2+5x+2x^2+7

## Step 1: Combining $x$ terms<br />### In $3x + 4x$, both terms contain $x$. Add the coefficients: $3+4=7$. The combined term is $7x$.<br /><br />## Step 2: Combining $x$ and constant terms<br />### In $8x - 3x + 2 - 5$, combine the $x$ terms: $8x - 3x = 5x$. Combine the constant terms: $2 - 5 = -3$. The simplified expression is $5x - 3$.<br /><br />## Step 3: Combining $x$, $y$, and constant terms<br />### In $2y + 3x + 4y - x + 10$, combine the $y$ terms: $2y + 4y = 6y$. Combine the $x$ terms: $3x - x = 2x$. The constant term is $10$. The simplified expression is $6y + 2x + 10$ or $2x + 6y + 10$.<br /><br />## Step 4: Combining $x^2$ and $x$ terms<br />### In $3x^2 + 5x + 2x^2 + 7$, combine the $x^2$ terms: $3x^2 + 2x^2 = 5x^2$. The $x$ term is $5x$. The constant term is $7$. The simplified expression is $5x^2 + 5x + 7$.