Quote:
Originally Posted by winders
Let's make it more clear:
Looking at it like this:
48 ÷ x(9 + 3) = 288
48 ÷ (9x + 3x) = 288
48/12x = 288
4/x = 288
4 = 288x
4/288 = x
1/72 = x
Or:
48 ÷ x(9 + 3) = 2
48 ÷ (9x + 3x) = 2
48/12x = 2
4/x = 2
4 = 2x
4/2 = x
2 = x
Would suggest that 288 is wrong, and that 2 is correct.
Like I said, the equation is poorly written as is designed to cause this kind of problem.
The equation should be written as:
48 ÷ 2 x (9 + 3) = 288
Or:
48 ÷ (2(9 + 3)) = 2
Scott
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multiplication and addition are associative so one can add parentheses where one wants
3*4*5 = (3*4)*5 = 3*(4*5) implicit or explicit has no bearing on this 3(4*5) = (3*4)5
but division and subtraction are not associative (3-4)-5 is not = 3-(4-5) in the absence of parenthesis in mixed expressions that contain operators of equal precedence are performed in strict left to right order
multiplication and division have equal precedence and so must be performed left to right, the parenthesis alters the precedence of addition
48 ÷ x(9 + 3) = 288
48 ÷ x(12) = 288 is correct but the next operation is division 48÷x then the multiplication by 12
here' are more that most will get wrong, what does each of these reduce to
2x/2x
2*x/2*x
2(x)/2(x)