Quick answer
Plot (k, aₖ) for an arithmetic sequence to get a straight line whose slope equals d in consistent units.
Formula
- Table: columns for k and aₖ
- Graph: slope ≈ d
Introduction
Tables and graphs do not replace algebra, but they make constant difference visible. That visibility helps you catch wrong d before you submit.
Build the list first with term-finding steps or the calculator, then organize results visually.
Formula reminders live in the arithmetic sequence formula article if you need to rebuild values from a₁ and d.
Table layout
Column 1: index k (1, 2, 3, …). Column 2: term value aₖ. Optional column 3: difference aₖ - aₖ₋₁ for self-checks.
Each row should match the calculator list exactly. Misaligned rows usually mean an indexing mistake, not a bad formula.
Tables export cleanly to spreadsheets for classroom reports or lab writeups.
Graph link and slope
- Plot points (k, aₖ)
- Slope between successive points equals d
- Linearity indicates arithmetic structure
When points fall on a line, constant difference is plausible. Curved patterns suggest geometric growth or another model.
Slope interpretation: vertical change over horizontal change between consecutive indices is d when k steps by 1.
Intercept on the vertical axis is not always a₁ because the graph uses index k, not time shifted elsewhere. Read axes carefully.
Step-by-step guide
- Generate the list. Compute terms with the formula or tool.
- Build the table. Pair each k with aₖ and optional difference column.
- Plot points. Use k horizontally and aₖ vertically unless the problem specifies otherwise.
- Estimate slope. Confirm slope matches d in the problem units.
- Interpret. Describe whether the pattern is linear and what d means in context.
Example table and graph story
Let a₁ = 5 and d = 3 for k = 1 through 4. Table values: (1,5), (2,8), (3,11), (4,14).
Successive slopes between points are 3, matching d. A plotted line rises steadily without curvature.
If a graph looks linear but differences in the table vary, trust the table subtraction over a rough visual guess.
