Combining LIke Terms

Which of these are like terms in the following expression:
3x + 7 - 9x + 24y + 2x²

• 7, 24y
• 3x, 9x
• 3x, -9x
• 3x, -9x, 2x²

Simplify by combining like terms:
5a + 2b - 3a + 4

• 8a + 2b + 4
• 2a + 2b + 4
• 8ab
• 4ab + 4

2r + 2 + 5r - 2 + r 

• 8r 
• 8r - 4 
• 12r 
• 7r + 4 + r 

Simplify by combining like terms:
5a + 2b - 3a + 4

• 8a + 2b + 4
• 2a + 2b + 4
• 8ab
• 4ab + 4

-4x - 10x

• -14
• 6x
• -6x
• -14x

Identify Like Terms
4r+2-6+2r

• 4r and 2r
• 2 and 6
• 4r and 2r,
   2 and 6
• 4r and 2r,
   2 and -6

• 24z+8
• 22z+6
• 23z+8
• 24z+2

• 5x+5y+18
• 6x+6y+10
• 5x+2y+18
• 5x +6y+10