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Equations: the solution (root)
Textbook Part 4, pp. 58–59
GoalUnderstand the root (solution) of an equation; write an equation for a problem and find its root.
New words
root (solution) · ildizvariable · o‘zgaruvchipark · istirohat bog‘i
Explanation
An unknown number shown by a letter is called a variable. The number that makes the equality true is the root (solution) of the equation. The root of x + 4 = 10 is 6, because 6 + 4 = 10.
Worked examples
A park has 23 plane trees, 21 maples, 5 oaks and some pines; 79 trees in all: 49 + x = 79 → x = 30 pines.
x − 20 = 40 → the root is 60 (60 − 20 = 40 ✓).
Class activity
“Find the root”: equations on the board, number cards for the children. Each child finds which equation their number solves and sticks it next to it.
Practice
1
23 + 21 + 5 + x = 79. x = ?
30
2
Is 8 the root of x + 9 = 17?
Yes, 8 + 9 = 17
3
x − 20 = 40. x = ?
60
4
50 − x = 30. x = ?
20