I think your expression is3st^2 / st + 6
where s = 4 and t =8.
I am a new member of this forum, and am eager to partake in many wonderful math discussions and offer as much help as I can!
My first post, however, is a bit of an embarrassing confession (especially considering I enjoy math so much that I teach it at the high school level)! I have an order of operations misunderstanding, it would seem, and am looking for some clarification.
The problem as given is:
3st^2 / st + 6
where s = 4 and t =8.
My understanding of the problem, then, is:
3*4*8^2 / 4 * 8 + 6
Order of operations state that parentheses ought to go first, then exponents, then multiplication or division, then addition or subtraction.
My order of solving the problem:
3*4*64 / 4 * 8 + 6 (exponents first)
12 * 64 / 4 * 8 + 6 (left to right multiplication or division)
768 / 4 * 8 + 6
192 * 8 + 6
1536 + 6 (addition)
Wolfram alpha did corroborate my answer: 3*4*8^2/4*8+6 - Wolfram|Alpha (although I'm not sure I used the proper division symbol)
However, this is not the answer that the book gives! The book gives an answer of 30. I can reproduce this answer IF I choose to multiply all my numbers first, then divide, then finish by adding.
Who is right? Is my understanding of Order of Operations flawed? Do I really need to complete all of my multiplication, then jump to division? I thought I merely went left to right on order of operations when I arrived at related operations (ie multiplication and division, or addition and subtraction).
Your notation is extremely ambiguous it could be either of
Apparently you mean the second. For the fraction, the order of multiplications or divisions is irrelevant- though it would be a good idea to do as much cancelling as possible.
Thanks for the replies, guys.
I completely see where simplifying the expression first, then substituting, then evaluating would be the ideal way to solve the problem. I'm teaching order of operations to brand new Algebra 1 students, however. I want to make sure I teach them the correct and accepted method for using order of operations.
I should have mentioned this: The division symbol that the book used was not the forward slash (and therefore it wasn't really a fraction) but the line with the two dots (one on the top and one on the bottom; the symbol that, for whatever reason, we are all first taught division with).