135
Equations
Textbook: Part 4, lesson 126, pp. 22–23
GoalUnderstand equation, unknown and root; find an unknown addend or factor.
New words
equation · tenglamaunknown · noma’lumroot (the solution) · ildizchecking · tekshirish
Explanation
An equation is an equality with an unknown number written as a letter. To solve it, we find the unknown. In x + 59 = 128 the unknown addend is x = 128 − 59 = 69. In 6 × c = 42 the unknown factor is c = 42 : 6 = 7. The number we find is the root of the equation. Check: 69 + 59 = 128.
Worked examples
x + 59 = 128, x = 128 − 59 = 69. Check: 69 + 59 = 128.
24 : f = 4, f = 24 : 4 = 6.
Class activity
“Mystery equation”: the teacher covers a number and says “□ + 3 = 10”. Children find the hidden number, write it as the equation “x + 3 = 10” and check the root.
Practice
1
x + 59 = 128, x = ?
69
2
x − 37 = 45, x = ?
82
3
6 × c = 42, c = ?
7
4
24 : f = 4, f = ?
6
5
A shop had x bowls. 28 were sold and 47 are left. How many bowls were there at first?
75