Rob is asked to simplify the expression below.

10x-2(4x+6y)+3y

He states that the simplified expression is 2x+15y because using the Distributive Property yields 10x-8x+12y+3y, and then combining like terms yields 2x+15y.

Explain the error in Rob' s reasoning.

Write the correct simplified expression for 10x-2(4x+6y)+3y. Show your work.



Answer :

Giovi
He forgot to change ALL the sign inside the bracket.
It should read:
10x-8x-12y+3y=2x-9y

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