__Objectives__

At the end of this lesson, students should be able to:

- Evaluate more complex algebraic expressions.

__Example 1__

Given that p=4, q=-2 and r=3, find the values of the following expressions:

**1**. 3(p + q) – 2(q + r)

**2**. (2p + r)^{2} – q^{2}

**3**. (2p + 3q + 4r)^{2}

__Solution__

**1**. 3(p + q) – 2(q + r) = 3(4 + (-2)) – 2(-2 +3)

= 3(4-2) – 2(-2 +3)

= 3(2) – 2(1)

= 6 – 2

= 4

**2**. (2p + r)^{2} – q^{2} = (2(4) + 3)^{2} – (-2)^{2}

= (8 + 3)^{2} – 4

= (11)^{2} – 4

= 121 – 4

= 117

**3**. (2p + 3q + 4r)^{2 } = (2(4) + 3(-2) + 4(3))^{2}

= (8 – 6 + 12)^{2}

= (14)^{2}

= 196

__Example 2__

If a = 2.4, b = 1.9, c = 1.1 and d = 0.6, find correct to one decimal place, the values of the following expressions: (You may use a calculator)

- d²
- c² + d²

__Solution____ __

- d² = d × d

= 0.6 × 0.6 = 0.36

**≈ 0.4 (≈ means Approximately)**

- c² + d² = (1.1)² + (0.6)²

= 1.21 + 0.36

= 1.57

**≈ 1.6**

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