x² + bx + c = 0: Error Analysis & Misconceptions

Mathematics
GCSE Foundation
13 questions
~26 mins
1 views0 downloads

About This Worksheet

A worksheet focusing on identifying and correcting misconceptions when solving quadratics of the form x² + bx + c = 0, with emphasis on error analysis and misconceptions.

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x² + bx + c = 0: Error Analysis & Misconceptions

Subject: MathematicsGrade: GCSE Foundation
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Untitled Worksheet

Grade GCSE Foundation
A

Introduction

Review the key formula: To solve x² + bx + c = 0 by factorising, find two numbers that multiply to c and add to b. Use these to factorise and solve for x.
B

Fluency & Practice

Answer all questions. Show your working in the grid spaces provided.
1.
Factorise the quadratic x² + 5x + 6 = 0 and find the solutions for x.
[3 marks]
2.
Solve the quadratic x² - 3x - 4 = 0 by factorising.
[3 marks]
3.
Factorise and solve: x² + 2x - 8 = 0.
[3 marks]
C

Problem Solving & Reasoning

Answer all questions with detailed working.
1.
A rectangle's area is represented by the quadratic x² + 7x + 10. Find the dimensions of the rectangle.
[4 marks]
2.
A student attempts to solve x² + 4x + 4 = 0 by factorising as (x + 2)^2 = 0. Identify and explain the mistake if any.
[4 marks]
3.
Explain why the quadratic x² + 2x + 3 cannot be factorised using real numbers.
[4 marks]
D

Real-world Applications

Answer all questions in detail.
1.
A ball is thrown upwards. Its height after t seconds is modeled by h(t) = -5t² + 20t + 2. Find when the ball hits the ground.
[4 marks]
E

Challenge & Extension

Attempt these more difficult problems.
1.
Given the quadratic x² + bx + 9 = 0, find the value of b if the roots are real and equal.
[3 marks]
2.
Construct a quadratic with roots at x = -1 and x = 4. Write its factorised form and solve for x.
[3 marks]
F

Mixed Review

Answer a variety of questions on solving quadratics.
1.
Solve the quadratic: 2x² + 8x + 6 = 0 by factorising.
[3 marks]
2.
Identify the error in solving x² - 6x + 9 = 0 as (x - 3)^2 = 0 and explain.
[3 marks]
G

Error Analysis & Misconceptions

Examine each problem and identify the mistake. Correct it and solve.
1.
A student factorises x² + 7x + 12 as (x + 3)(x + 4) and finds solutions. Is this correct? If not, identify and correct the mistake.
[4 marks]
2.
A student attempts to solve x² + 2x + 1 = 0 by cancelling the common factor (x + 1) from numerator and denominator. Explain why this is incorrect.
[4 marks]

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Details

Created
1/1/2026
Updated
1/1/2026
Type
worksheet