Question 882037
(4 + 6x + 9x² + 7x³) + (7 - 6x + 9x² - 7x³)
= 4 + 6x + 9x² + 7x³ + 7 - 6x + 9x² - 7x³   {removed parentheses}
= 18x² + 11 {combined like terms}
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