Worked Example 1
Simplify 7x + 3y − 2x + 5y − 4.
Sort the terms into kindsx terms: 7x and −2x. y terms: 3y and 5y. Constant: −4
Combine each kind5x, 8y and −4
Write the answer5x + 8y − 4
Check with numbersWith x = 1 and y = 1, both give 9. That check takes ten seconds.
Worked Example 2
If a = 4 and b = −3, find the value of 3a² − 2ab.
Replace the letters, using brackets3 × 4² − 2 × 4 × (−3)
Powers before multiplication4² = 16, so the first term is 48
The second term2 × 4 × (−3) = −24, and subtracting −24 adds 24
Answer72
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