Example 1 · level 1
Add 4x + 9y and 2x + 9y.
- 2x + 18y
- 6x
- 2x
- 6x + 18y
Show solution
- (4x + 9y) + (2x + 9y)
- x: 4 + 2 = 6; y: 9 + 9 = 18.
- Answer: 6x + 18y.
Answer: 6x + 18y
CLASS 7 MATHS · ALGEBRAIC EXPRESSIONS
Add and subtract algebraic expressions
Only like terms (same letters with the same powers) can be combined: add or subtract their coefficients.
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Worked examples
Example 2 · level 2
Add 4x − y and 7x + 2y.
- 11x + y
- −3x − 3y
- 11x − 3y
- −3x + y
Show solution
- (4x − y) + (7x + 2y)
- x: 4 + 7 = 11; y: −1 + 2 = 1.
- Answer: 11x + y.
Answer: 11x + y
Example 3 · level 3
Add 7x² + 6x − 1 and −7x² − x + 9.
- 14x² + 7x − 10
- 7x + 8
- 5x + 8
- 14x² + 5x + 8
Show solution
- (7x² + 6x − 1) + (−7x² − x + 9)
- x²: 7 + (−7) = 0; x: 6 + (−1) = 5; numbers: −1 + 9 = 8.
- Answer: 5x + 8.
Answer: 5x + 8