Year 9

Year 9

Difference of two squares

Lesson details

Key learning points

1. In this lesson, we will learn about the difference of two squares. We will investigate the pattern of results when considering multiplying out brackets of the general form (x+a)(x-a).

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6 Questions

Q1.
Choose the word which best fills the gap: When we ________ double brackets every term in the first bracket must be multiplied by every term in the second bracket.
divide
express
factorise
Q2.
Expand and simplify (x+2)(x+5)
18x²
x² + 10
x² + 17x
Correct answer: x² + 7x + 10
Q3.
Expand and simplify (x+2)(x-5)
x² - 10
Correct answer: x² - 3x - 10
x² - 7x + 10
x² + 3x + 10
Q4.
Expand and simplify 2(x+3)-2(x+5)
-4x
2x² - 6x + 20
Q5.
A rectangle has side lengths (x+4) and (x-3). Match the expression that would represent it's area.
20x²
x² - x + 12
x² + 7x - 12
Correct answer: x² + x - 12
Q6.
Yasmin expanded (a + x + 3)(x + 2). Below are her workings out. Which expression matches the area of the rectangle she has created?
13ax²
ax² + 7ax + 6
x² + a + 5x + 8a
Correct answer: x² + ax + 5x + 2a + 6

6 Questions

Q1.
Which expression is equivalent to a² - b² ?
(a - b)(a - b)
Correct answer: (a + b)(a - b)
2ab
ab
Q2.
Match the expression equivalent to (x+4)(x-4).
x² - 16x
x² - 4
x² - 8x + 16
x² + 4²
Q3.
Match the expression equivalent to (x+9)(x-3).
Correct answer: None of the above.
x² - 3²
x² - 6²
x² + 3x - 27
Q4.
Which calculation would work out 64² - 4² ?
(8 x 2)²
60 x 60
72 x 6
Q5.
Match the expression equivalent to (x+25)-(x-25).