What this guide covers
Selected Sec 1 N7 skills: one-variable linear equations and simple contextual formulation. Simultaneous equations and quadratic equations are later work.
Undo operations, then check
If a whole expression is divided by a number, undo the division first. Substitute the proposed answer into the original equation, not only the last line of working.
A fraction can still be linear
Solve (x+3)4=5.
- Multiply both sides by 4: x+3=20.
- Subtract 3 from both sides: x=17.
Check: In the original equation, (17+3)4=204=5.
Try it yourself
Work on paper, then compare the steps. These checks do not establish mastery.
Solve x3+2=7 and check the value.
Subtract 2: x3=5. Multiply by 3: x=15. Check: 153+2=7.
Three identical notebooks and a $4 delivery charge cost $25. Form an equation and find one notebook's price.
Let p be one notebook's price in dollars. Then 3p+4=25, so 3p=21 and p=$7. Check: 3($7)+$4=$25.
Where this connects
- Earlier: brackets and signs →
Accurate expansion helps when an equation contains brackets.
- Next: two equations →
Sec 2 uses two related equations to find two unknowns.
Sources and scope
Original Mentora examples and checks aligned to Sec 1 N7 in the MOE G2/G3 Mathematics syllabus. No school-paper text was reused.