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How do you simplify 15-10(x-4)-(3x+3)?15-10(x-4)-(3x+3) my answer was:...

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cookiee-monster | Student, Grade 11 | (Level 1) Honors

Posted November 9, 2011 at 5:18 AM via web

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How do you simplify 15-10(x-4)-(3x+3)?

15-10(x-4)-(3x+3)

my answer was:

15-10(x-4)-(3x+3)

= 15x-60-10x+40-3x-3

= 2x-23

 

But the answer on the back of the book said it's -13x+52

I'm confused-.-

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taylormath | High School Teacher | (Level 2) Adjunct Educator

Posted November 9, 2011 at 5:35 AM (Answer #1)

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Thanks for showing your work above.  The mistake that you make is that you included an x on the 15.

The problem starts: 15-10(x-4)-(3x+3)

You do a great job distributing the -10 and negative.  The 15 just doesn't get an x.

15 - 10x + 40 - 3x - 3

(-10x - 3x) + (15 + 40 - 3)

Combing like terms: -13x + 52

It looks like you understand the concept of distributing and combining like terms very well.  I know when answers don't match the back of the book, it can be very frustrating.  Keep up the hard work/effort and I think you'll notice these types of mistakes diminishing.

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