Question 82319
YOU NEED TO BREAK THESE TYPE OF PROBLEMS INTO 2 PARTS THUS: 
X(5X+3)=5X^2+3X
7(5X+3)=35X+21
NOW WE NEED TO ADD THESE TWO PIECES.
5X^2+3X+35X+21
5X^2+38X+21
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5X+3
X+7
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5X^2+3X+35X+21 NOW COMBINE LIKE TERMS
5X^2+38X+21