Mathematics (VII

Abdullah Al Mahmud

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Linear Equations in One Variable

Topics

  • Equations
  • Linear Equations

Linear Equations

  • ax + by = c (two variables)
  • ax + by + cz = d (3 variables)

Visual Equations

Rules of Equation

Same amount can be

  • added
  • subtracted
  • multiplied
  • divided

on both side

\(3x-7=15 \rightarrow\)

Examples of Rules

  • x + 2 = 6
  • x - 4 = 1
  • 4x + 10 = 22
  • \(12x = 14\) from \(\frac{3x}{2}=\frac74\)
  • \(3x+2=2x+1\) from \(5(3x+2)=5(2x+1)\)

Problem 01

The height of Tajindong, the highest mountain peak of Bangladesh is 295 metre more than Keokaradong, the second highest mountain peak of Bangladesh. If the height of Tajindong is 1280 metre, then let us find the height of Keokaradong.

Problem 02

There was a “safe hand wash programme” in Kabi Nazrul High School. There were 42 students absent in that programme and 915 students participated in the programme. Find the total number of students.

Problem 03

Salam gets 300 taka per hour every day for his overtime work. He bought a mobile phone this month with 9000 taka received for overtime work. What is the total hour of his overtime work?

Problem 04

A shark can swim at an average speed of 20 miles per hour. What is the distance that he can cover swimming in 24 hours at this speed?

Solve by Cutting Paper

\(x + 3 = 3\)

Individual Tasks

  • What is the number when adding 5 to the double of it will give the sum 25?
  • Sum of two numbers is 55 and 5 times the bigger number is equal to 6 times the smaller number. Find the two numbers.
  • Gita, Rita and Mita together have 180 taka. Gita has 6 taka less than Rita and Mita has 12 taka more. Determine who has what amount?