Homework Help: Grade 9 Algebra Question 2

Posted by Jab on Thursday, October 6, 2011 at 7:06pm.

2. PYRAMIDS When climbing an ancient
Mayan pyramid, the Johnson family
noticed that the bottom of each side of the pyramid started with 50 large
stones. The next step up had 45 large
stones, the next step up had 40 stones, and so on. Write an equation to represent the number of stones on each level. How many levels can the pyramid
have?

Steps 1 = 45 stones
Steps 2 = 40 stones
Steps 3 = 34
?

Grade 9 Algebra Question 2 - Reiny, Thursday, October 6, 2011 at 7:14pm
Do you have a typo for steps 3= 34 , should it be 35?

level 0 = 50
level 1 = 45
level 2 = 40
...
level n = -5n + 50

so if level n = 0
-5n+50=0
-5n=-50
n=10

counting ground level (level 0) there would be 11 levels
Grade 9 Algebra Question 2 - Jab, Thursday, October 6, 2011 at 7:29pm
yes its a typo! 35
Grade 9 Algebra Question 2 - Jab, Thursday, October 6, 2011 at 7:31pm
I like how you explain it. I now understand. Thanks Reiny!

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