140
Solving problems with equations
Textbook Part 4, pp. 60–61
GoalSolve problems by writing an equation; understand inverse problems.
New words
inverse problems · o‘zaro teskari masalalarwrestling (kurash) · kurashathlete · sportchi
Explanation
One situation gives three problems: find the whole (10 + 6 = 16), find the first part (16 − 6 = 10) and find the second part (16 − 10 = 6). These are inverse problems. We call the unknown x and write an equation.
Worked examples
Feruz drew 15 sport symbols and together they drew 37: 15 + x = 37 → x = 22 (Komil).
At a tournament 10 wrestlers did freestyle and 6 did Uzbek kurash: 10 + 6 = 16 athletes.
Class activity
The class splits into three groups. From one situation (e.g. 12 girls and 9 boys) each group writes one of the inverse problems and solves it with an equation.
Practice
1
15 + x = 37. x = ?
22
2
16 athletes in a tournament; 6 in Uzbek kurash. How many in freestyle? Write an equation.
x + 6 = 16, x = 10
3
Make 4 equalities with 4, 6 and 10.
4 + 6 = 10, 6 + 4 = 10, 10 − 4 = 6, 10 − 6 = 4
4
Simplify and solve: x + 2 + 3 = 15
x + 5 = 15, x = 10