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Which of the following is equivalent to (-7x^3+5ax-3) + (7x^3+5-9ax)?A. 14x^3 - 4ax +...

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voclomer90 | Student, Grade 9 | eNotes Newbie

Posted January 10, 2012 at 6:10 AM via web

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Which of the following is equivalent to (-7x^3+5ax-3) + (7x^3+5-9ax)?
A. 14x^3 - 4ax + 2
B. x^6 - 4ax + 2
C. -4ax + 2
D. -49x^3 - 45ax - 15

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tariqqqq | Student, Undergraduate | (Level 1) Honors

Posted January 10, 2012 at 7:36 AM (Answer #1)

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(-7x^3+5ax-3) + (7x^3+5-9ax)  ---- (multiply the equation on the right by (+). Step 1.

-7x^3+5ax-3 + 7x^3+5-9ax   ------  (-7x^3+7x^3=0).Step 2.

5ax-3+5-9ax   ---- (5ax-9ax=-4ax).Step 3.

-4ax-3+5   --- (-3+5=2). Step 4.

-4ax+2. Step 5.

"C" is the right the equivalent equation for (-7x^3+5ax-3) + (7x^3+5-9ax). I hope my explainations helped you to understand :). Feel free to message me for anymore questions.

 

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted January 11, 2012 at 5:08 PM (Answer #2)

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The question involves direct addition of terms that are alike.

(-7x^3+5ax-3) + (7x^3+5-9ax)

Open the brackets

-7x^3 + 5ax - 3 + 7x^3 + 5 - 9ax

Take the alike terms together

=> -7x^3 + 7x^3 + 5ax - 9ax - 3 + 5

=> 0 - 4ax + 2

The required result is -4ax + 2, which is option C.

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