Xiao Huang does a question "known two polynomials a, B, calculate A-B". Xiao Huang mistakenly regards A-B as a + B, and the result is 9x2-2x + 7. If B = x2 + 3x-2, please help Xiao Huang find the correct answer of a-b

Xiao Huang does a question "known two polynomials a, B, calculate A-B". Xiao Huang mistakenly regards A-B as a + B, and the result is 9x2-2x + 7. If B = x2 + 3x-2, please help Xiao Huang find the correct answer of a-b

∵A+B=9x2-2x+7,B=x2+3x-2,∴A=9x2-2x+7-(x2+3x-2)=9x2-2x+7-x2-3x+2=8x2-5x+9,∴A-B=8x2-5x+9-(x2+3x-2)=8x2-5x+9-x2-3x+2=7x2-8x+11.