Please solve questions no twenty one and questions eighteen of this attachment of questions

It seems like you're referring to specific questions from an attachment, but unfortunately, I can't access external files or attachments. However, I can certainly help you with similar questions or concepts if you provide the details of questions eighteen and twenty-one. Just type them out here, and I'll guide you through the solutions step by step!

Breaking Down the Problem

When tackling any question, especially in subjects like math or science, it's essential to first understand what the question is asking. Look for keywords and phrases that indicate the operations or concepts involved. For example, if a question involves calculations, identify whether it requires addition, subtraction, multiplication, or division. If it's a conceptual question, focus on the main idea or theory being tested.

Steps to Approach a Question

• Read Carefully: Make sure you understand the question fully. Look for any specific instructions.
• Identify Key Information: Highlight or note down important numbers, terms, or concepts.
• Plan Your Approach: Decide on the method or formula you will use to solve the problem.
• Execute: Carry out your plan step by step, ensuring accuracy at each stage.
• Review: Once you have an answer, double-check your work to catch any mistakes.

Example Problem Solving

Let’s say question eighteen is about solving a quadratic equation, and question twenty-one involves calculating the area of a triangle. Here’s how you might approach each:

Solving a Quadratic Equation

For a quadratic equation like ax² + bx + c = 0, you can use the quadratic formula:

x = (-b ± √(b² - 4ac)) / 2a

1. Identify the coefficients a, b, and c from your equation.

2. Plug these values into the formula.

3. Calculate the discriminant (b² - 4ac) to determine the nature of the roots.

4. Solve for x using both the positive and negative square root.

Calculating the Area of a Triangle

The area of a triangle can be found using the formula:

Area = 1/2 × base × height

1. Identify the base and height of the triangle from the problem.

2. Substitute these values into the formula.

3. Perform the multiplication and division to find the area.

Once you provide the specific questions, I can guide you through the exact steps needed to solve them. Just let me know what they are!