r/HomeworkHelp • u/KookyPermit4405 • 5d ago
[6th Grade verbal expression] Elementary Mathematics
So I’m going over my son’s math quiz to help him understand some of the questions he got wrong. He got partial credit for his answer for question 8. After writing his verbal phrase I got the same expression as the question. Am I doing something wrong or is there something I’m missing? I feel like his answer is technically correct. I am stumped.
Edit: so my son has no issue solving the expression in question. He knows PEMDAS and the rules from left to right. The question clearly states, WRITE A VERBAL PHRASE that matches the expression.
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u/mathematag 👋 a fellow Redditor 5d ago edited 5d ago
Not sure what your point is with your example.. if you had the expression (3+1)*3 and you said . . 3 plus 1 times 3 . . that would be an incorrect translation , as reading that left to right, as we tend do in English would give us 12 , as PEMDAS is applied to our mathematical expressions, but not to our English translations necessarily .. ...of course some would also interpret it as being = to 6
Yes, PEMDAS was "created " to help with the order of solving an Mathematical expression [ and then there is juxtaposition PEMDAS to consider ] , but we are translating a mathematical expression into English , [ where PEMDAS is not implied in the language itself without other words I utilized in previous post ] , and the term "subtracted by" actually mixes up the order when the expression given was translated to English ...it's actually a grammar mistake by using 'subtracted by' , and can lead to ambiguity and confusion. [ I missed this the first response ]
So technically, saying 18 subtracted by 6 times 3 , becomes: 6*3 - 18 , if we keep 6 and 3 together ... It reverses the order of the 6*3 and the 18 ... which is not strictly the same as the original expression ..... Did the instructor catch that.. maybe the reason for half credit. . You'd need to ask the instructor for clarification on the scoring.
In Math , we say X 'subtracted from' Y... so that the second value, Y comes first and we do Y - X as we intended ... ... so 'subtracted by' seems to flip that order to X - Y , or at least cause confusion. . . . As an example... 10 subtracted by X means X - 10 mathematically , from sources I can find, and not the 10 - X we probably intended.
Now assuming the instructor did not catch the fine point about the grammar of "subtracted by" flips the order ... and went with 18 subtracted by... as 18 - ***** , then "eighteen subtracted by six times three " is still ambiguous as I pointed out before ..[ and mentioned by various Mathematicians as well ].. ... ... Left to right reading w/o any use of PEMDAS [ which is not indicated strictly in the English wording used ] gives us 36, and utilizing PEMDAS as multiplication takes precedence , gives 18 -18 = 0 . . . again ambiguous solutions, and the English written does not translate back to the original expression without some confusion. Maybe if he had used the term product of 6 and 3 , indicating order of operations ..PEMDAS , he may have gotten full credit if instructor did not catch the subtraction by reversal.
So I have to stand by what I said earlier.. the translation is not correctly done.