Quadratic formula
Edexcel GCSE Maths revision on Quadratic formula. Aligned to the Pearson Edexcel GCSE Mathematics 1MA1 specification. This bank has 16 practice questions on this topic.
Sample questions (3 of 16)
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Question 1
What is the value of the discriminant for the equation 2x squared plus 5x plus 2 equals 0?
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Answer: 9
For the equation 2x^2 + 5x + 2 = 0, a=2, b=5, and c=2. Calculating b^2 - 4ac gives 25 - 4(2)(2), which equals 25 - 16, resulting in 9.
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Question 2
Which expression represents the correct quadratic formula for solving ax squared plus bx plus c equals 0?
- A) x equals negative b plus or minus root b squared minus 4ac all divided by 2a
- B) x equals negative b plus or minus root b squared minus 4ac all divided by 2c
- C) x equals positive b plus or minus root b squared minus 4ac all divided by 2a
- D) x equals negative b plus or minus root b squared plus 4ac all divided by 2a
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Answer: x equals negative b plus or minus root b squared minus 4ac all divided by 2a
The correct formula is x = (-b ± √(b^2 - 4ac)) / 2a. A common error is misremembering the sign of b or the operation inside the square root.
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Question 3
What is the positive solution to the equation x squared plus 3x minus 4 equals 0?
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Answer: 1
Using the quadratic formula, the roots are (-3 ± √(9 - 4(1)(-4))) / 2. This simplifies to (-3 ± √25) / 2, giving -4 and 1, where 1 is the positive solution.
Want to test yourself on the remaining cards for this topic?
13 more questions on Quadratic formula — plus mistakes tracking and spaced repetition across the whole Maths spec.