Write an expression for the topmost row of a pyramid with 4 rows in terms of the values in the bottom row.
Given: Bottom row values: a, b, c, d
Pattern: For a 3-row pyramid with bottom row a, b, c, the top is a + 2b + c.
Extension: For a 4-row pyramid, the coefficients follow the third row of Pascal's triangle: 1, 3, 3, 1.
Answer: Topmost row = a + 3b + 3c + d
Explanation
The chapter shows that for a 3-row pyramid with bottom row a, b, c, the top is a + 2b + c. Extending this pattern, for a 4-row pyramid, the coefficients follow the third row of Pascal's triangle: 1, 3, 3, 1.
Solution Steps
Identify the bottom row values: a, b, c, d
Recognize the pattern from a 3-row pyramid: top = a + 2b + c
Apply Pascal's triangle coefficients (1, 3, 3, 1) for a 4-row pyramid
Write the expression: a + 3b + 3c + d