# Chapter 7.3 (Graphs)

## Coccept of graph

Imagine you are at your home. You came out and went 10m eastward and 5m southward. Where is you current location?

• This point is called (10,5)

## Know this man?

Where would these points be?

Mention that “lengths of the side of the smallest square as unit along both axes.”

• (10,2)
• (-10,2)
• (10,-5)
• (-10,-5)

• A (5,3)
• B (5,-3)
• C (-5,3)
• D (-5,-3)

## Find the geometric shape from this coordinates

1. (3,2); (6,2); (6,4); (3,4)
2. (0,4); (2,2); (4,0)
3. (2,0); (3,4); (4,0)

Draw these points. What are the shapes?

## Plotting an Equation

y = 3x + 5

If x = 2, 3, 4, 5

$$y=3 \times 2 + 5 = 11$$

## Solving Equation with Graph

First solve manually

1. Solve and show solutions using graphs
1. x-4=0
2. 2x+1 = x-3
• Classwork: 3x+4 = 5x

## Solve by Graph

5x+4 = 4x + 7; without solving mathematically

## Exercise 7.3 (14)

Length of three sides of a triangle are (x+2), (x+4), and (x+6) cm (x>0). Perimeter of the triangle is 18 cm.

1. Draw a proportional figure using the conditions.
2. Formulate and solve.
3. Draw the graph of the solution.

## Exercise 7.3 (15)

Distance between Dhaka and Aricha is 77 km. A bus starts from Dhaka to Aricha at 30 kmh, and another from Aricha to Dhaka at 40 kmh. The two meet at x km from Dhaka.

1. How far from Aricha will they meet? Express in terms of x.
2. Determine x
3. How much time will each bus take to reach their destinations?

## Extra Exercise 01

Solve

$$5x^2+6x+18=4x^2+9$$

• $$x^2+5x+6=0$$