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Tyler is simplifying the expression: 6-2x+5+4x Here is his work

6-2x+5+4x
(6-2)x+(5+4)x
4x+x
13x

a. Explain the error he made

b. Simplify the expression: 6-2x+5+4x

1 Answer

6 votes

Answer:

11-2x not 13x

Explanation:

\(6-2)x + (5-4)x does = 13x

If there were parentheses as in the 2nd line, everything else is correct

the mistake is going from

6-2x + 5-4x to

(6-2x) + (5-4)x

PEMDAS is the order of operations. P for parentheses 1st, Multiplication 3rd, addition 4th, subtraction 5th

(there are no exponents or division or parentheses, so it's just M, A and S that apply)

combine like terms, 2x-4x =-2x

combine the constant terms 6+5 = 11

6-2x +5-4x = 11-2x

The mistake was assuming parentheses when they aren't there.

correct answer is 11-2x not 13x

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