Chapter 2: Introduction to Linear Polynomials

Exercise

Question

Question: 5

5 / 5

Sarita is reading a book of 500 pages. She reads 20 pages every day. How many pages will be left after 15 days? Express this as a linear pattern.

Answer

1
Start with 500 pages and subtract 20 pages for each day she reads.
After 1 day: 500 - 1 × 20 = 500 - 20 = 480
After 2 days: 500 - 2 × 20 = 500 - 40 = 460
After 3 days: 500 - 3 × 20 = 500 - 60 = 440
2
Write the number of pages left after d days as a linear expression.
\text{Pages left after $d$ days = $500 - 20d$ $\quad$ ${color:#625b5f}[Initial number of pages is 500; 20 pages are read each day]{/color}$}
3
Substitute d = 15 into the expression and simplify.
Pages left after 15 days:
⇒
\text{ $500 - 20 × {color:#2E2EFF}15{/color}$}
⇒
$500 - 300$
⇒
$200$ pages
4
Write the number of pages left after 15 days.
Answer: 200 pages will be left after 15 days.
5
Write the linear pattern for the number of pages left.
Answer: The linear pattern is 480, 460, 440, …, with a common difference of −20 pages.
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