Explore a diverse range of topics and get answers from knowledgeable individuals on IDNLearn.com. Discover prompt and accurate responses from our experts, ensuring you get the information you need quickly.

Macheountio Grade 10 Paper 1

Question 3

3.1 Solve for [tex]\( x \)[/tex]:
3.1.1 [tex]\( x(x-2)=8 \)[/tex]
3.1.2 [tex]\( 3^{2x+2}=\frac{1}{27} \)[/tex]

3.2 Solve the following inequality and represent it graphically:
[tex]\[
-\frac{1}{3}\ \textless \ \frac{x-1}{6}\ \textless \ \frac{1}{18}
\][/tex]

3.3 A fruit yoghurt costs [tex]\( R 4 \)[/tex] more than a plain yoghurt. It is further given that 5 fruit yoghurts and 3 plain yoghurts together cost [tex]\( R 84 \)[/tex].

3.3.1 Assign variable [tex]\( x \)[/tex] to the price of fruit yoghurt and [tex]\( y \)[/tex] to the price of plain yoghurt and set up a system of equations.
3.3.2 Using the above equations, determine the individual prices of the yoghurts.


Sagot :

Alright, let's work through each part of the question in detail:

### 3.1 Solve for [tex]\(x\)[/tex]

#### 3.1.1 [tex]\(x(x-2)=8\)[/tex]

1. Expand the left side of the equation to get a quadratic equation:
[tex]\[ x^2 - 2x = 8 \][/tex]
2. Subtract 8 from both sides to set the equation to zero:
[tex]\[ x^2 - 2x - 8 = 0 \][/tex]

3. Factorize the quadratic equation:
[tex]\[ (x - 4)(x + 2) = 0 \][/tex]

4. Solve for [tex]\(x\)[/tex]:
- [tex]\(x - 4 = 0\)[/tex] [tex]\(\Rightarrow\)[/tex] [tex]\(x = 4\)[/tex]
- [tex]\(x + 2 = 0\)[/tex] [tex]\(\Rightarrow\)[/tex] [tex]\(x = -2\)[/tex]

Therefore, the solutions are:
[tex]\[ x = 4 \text{ or } x = -2 \][/tex]

#### 3.1.2 [tex]\(3^{2x + 2} = \frac{1}{27}\)[/tex]

1. Recall that [tex]\(27 = 3^3\)[/tex], so [tex]\( \frac{1}{27} = 3^{-3} \)[/tex].

2. Set the exponents equal to each other:
[tex]\[ 2x + 2 = -3 \][/tex]

3. Solve for [tex]\(x\)[/tex]:
[tex]\[ 2x + 2 = -3 \][/tex]
[tex]\[ 2x = -5 \][/tex]
[tex]\[ x = -\frac{5}{2} \][/tex]

However, the solution is:
[tex]\[ x = -2.5 \text{ (This also includes a complex component, } -2.5 + 2.85960086738013i\text{)} \][/tex]

### 3.2 Solve the following inequality and represent it graphically:

[tex]\[ -\frac{1}{3} < \frac{x-1}{6} < \frac{1}{18} \][/tex]

1. Split the compound inequality into two parts and solve each part separately.

#### Part 1:
[tex]\[ -\frac{1}{3} < \frac{x-1}{6} \][/tex]

2. Multiply both sides by 6 to clear the denominator:
[tex]\[ -2 < x - 1 \][/tex]
3. Add 1 to both sides:
[tex]\[ -1 < x \][/tex]

So, the first inequality is:
[tex]\[ x > -1 \][/tex]

#### Part 2:
[tex]\[ \frac{x-1}{6} < \frac{1}{18} \][/tex]

4. Multiply both sides by 18 to clear the denominator:
[tex]\[ 3(x - 1) < 1 \][/tex]

5. Divide both sides by 3:
[tex]\[ x - 1 < \frac{1}{3} \][/tex]

6. Add 1 to both sides:
[tex]\[ x < \frac{4}{3} \][/tex]

So, the second inequality is:
[tex]\[ x < \frac{4}{3} \][/tex]

Combining both parts, we get the solution for the compound inequality:
[tex]\[ -1 < x < \frac{4}{3} \][/tex]

The range of [tex]\(x\)[/tex] is:
[tex]\[ -1 < x < 1.33333333333333 \][/tex]

### 3.3 Determining the prices of yoghurts

#### 3.3.1 Assign variables:

Let:
- [tex]\(x\)[/tex] be the price of a fruit yoghurt.
- [tex]\(y\)[/tex] be the price of a plain yoghurt.

We are given two pieces of information:
1. A fruit yoghurt costs [tex]\(R 4\)[/tex] more than a plain yoghurt:
[tex]\[ x = y + 4 \][/tex]

2. Five fruit yoghurts and three plain yoghurts together cost [tex]\(R 84\)[/tex]:
[tex]\[ 5x + 3y = 84 \][/tex]

#### 3.3.2 Determine the individual prices of the yoghurts

1. We have the system of equations:
[tex]\[ x = y + 4 \][/tex]
[tex]\[ 5x + 3y = 84 \][/tex]

2. Substitute [tex]\(x = y + 4\)[/tex] into the second equation:
[tex]\[ 5(y + 4) + 3y = 84 \][/tex]

3. Expand and simplify:
[tex]\[ 5y + 20 + 3y = 84 \][/tex]
[tex]\[ 8y + 20 = 84 \][/tex]
[tex]\[ 8y = 64 \][/tex]
[tex]\[ y = 8 \][/tex]

4. Substitute [tex]\(y = 8\)[/tex] back into the first equation:
[tex]\[ x = y + 4 \][/tex]
[tex]\[ x = 8 + 4 \][/tex]
[tex]\[ x = 12 \][/tex]

Therefore, the individual prices are:
[tex]\[ \text{Price of fruit yoghurt } x = 12 \][/tex]
[tex]\[ \text{Price of plain yoghurt } y = 8 \][/tex]