the equation was
3+2[10(7*5-30)-40]
and it bacame
3+2[10(35+ -30)+ -40]
Why? and How?
the equation was
3+2[10(7*5-30)-40]
and it bacame
3+2[10(35+ -30)+ -40]
Why? and How?
Read it phonically!
3+2[10(35+ -30)+ -40]
three plus two "OPEN SQUARE BRACKET" times ten "OPEN PARENTHESES BRACKET" thirty five plus negative thirty "CLOSE PARENTHESES BRACKET" plus negative 40 "CLOSE SQUARE BRACKET"
This often helps, I have the student read me what they think it says, then have them space by space read me what they are seeing, and directing on minus versus negative etc.
Subtraction can always be thought of as adding a negative number.
For example, 1 - 1 is the same as 1+ -1.
I love that your calculator shows this! It looks weird at first, but if you get used to thinking of "subtracting" as "adding a negative number", it will help you as you get into more advanced algebra.
This is simply a matter of formatting, although it is unusual for a calculator to be formatted this way. Basically the calculator applied the order of operations (PEMDAS: Parentheses, Exponents, Multiplication, Division, Addition, and Subtraction). First, it carried to the first process in the order of operations which is the multiplication of the 7 and 5 within the parentheses. Then tt seems as if your calculator frameed the recipricol operations multiplication/division and addition/subtraction as only one of the operations. In this case the subtraction problem 35-30 is translated into the equivelent 35+ -30. Adding a negative number is the same as subtracting a positive number thus the -40 is also changed to +-40. It is certaintly an odd thing for a calculator to do but it does make a certain element of sense for the order of operations can be misleading. PEMDAS is supposed to be heirarchy where each letter represents the process that is carried out before the following letter however, multiplication and division actually make up the same tier of the heirarchy as do Addition and Subtraction (being that they are correlated processes). Accordingly, to make up for this it seems that your calculator frames all Addition/Subtraction problems in terms of addition and will like frame all multiplication/division problems in terms of multiplication making the effective order of operations for your calculator PEMA (Parenthesis, Exponents, Multiplication, Addition).
Comments
Just as a disclaimer: I have never actually seen a calculator do this before and so this is simply an educated hypothesis, albeit one that is grounded in the evidence, and must be taken as such. Still, the more important part is that the second equation displayed by your calculator is identitical to the input equation and will still lead to the same answer if you know how to read it.