OG详解-OG9 数学1 Q5

Choice A is correct. Since x is a factor of each term in the given expression, the expression is equivalent to x(9x)+x(5), or x(9x+5).
Choice B is incorrect. This expression is equivalent to 45x² +5x, not 9x² +5x. Choice C is incorrect. This expression is equivalent to 9x² +45x, not 9x² +5x. Choice D is incorrect. This expression is equivalent to 9x³ +5x² , not 9x² +5^x.