Writing Algebraic Equations
Express missing number problems algebraically using letters for unknowns; translate word problems into equations
Ce que l'enfant saura faire ensuite
- Write 'I think of a number, double it, and add 5 to get 17' as 2n + 5 = 17
- Solve a one-step equation such as 3x = 24 and explain the reasoning
- Express a word problem as an algebraic equation and find the unknown value
1 · Lis
You already know how to write number sentences with a blank, like 5 + □ = 12. In algebra, you swap the blank for a letter, such as n or x. That letter is called a variable, and it stands for the number you are trying to find.
Zara says, 'I think of a number, triple it, and subtract 4 to get 11.' Let n be her number. Tripling means multiply by 3, so the equation is 3n - 4 = 11. Add 4 to both sides: 3n = 15. Divide both sides by 3: n = 5.
To find the unknown, undo what was done to it. Addition undoes subtraction, and division undoes multiplication. Undo the last operation first.
Turn the words into a letter and symbols, then undo each operation to find the unknown number.
Readings 'Turning words into symbols', 'A plan for word problems' and 'Undoing the steps' are original to this dataset. All 9 extra questions are original to this dataset.
2 · Regarde
En anglaisSans écran
Où se situe ce sujet
À apprendre avant
Liens facultatifs
Où cela peut mener
Les métiers qui s'appuient sur cette compétence. En suivre un pour voir tout ce sur quoi il repose.
17 questions attendent derrière cette leçon, chacune avec sa réponse expliquée. Chaque réponse nourrit le ciel : les étoiles s'allument à mesure qu'elles sont apprises, et pâlissent quand vient le moment de revenir.