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Substitution Calculator
Replace the letters in an expression with numbers and work out the value. Negatives go in inside brackets, which is the habit that stops a squared term losing its sign, and the order of operations is followed line by line. Choose a linear, quadratic or two letter expression to match your question.
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Worked Example
Work out 2x² − 3x + 4 when x = −5.
- Swap x for its value in brackets: 2 × (−5)² − 3 × (−5) + 4
- Squaring comes first:(−5)² = 25, positive because a negative times a negative is positive
- Now the multiplications:2 × 25 = 50, and −3 × (−5) = 15
- Add it all up:50 + 15 + 4 = 69
Answer: 69
Try These Yourself
Work out 3x + 7 when x = −2.Show answer
Answer: 1
3 × (−2) = −6, then −6 + 7.
Work out x² + x when x = −3.Show answer
Answer: 6
9 + (−3) = 6.
Work out 4x + 5y when x = 2 and y = −1.Show answer
Answer: 3
8 + (−5) = 3.