A student is doing a question: "given two polynomials A and B, calculate 2A + B", If we mistakenly regard "2A + B" as "a + 2B", the result is 9x square - 2x + 7

A student is doing a question: "given two polynomials A and B, calculate 2A + B", If we mistakenly regard "2A + B" as "a + 2B", the result is 9x square - 2x + 7

A+2B=9X²-2X+7
B=X²+3X-2
A=9X²-2X+7-2B
=9X²-2X+7-2(X²+3X-2)
=7x²-8x+11
Correct answer:
2A+B
=2(7x²-8x+11)+X²+3X-2
=14x²-16x+22+x²+3x-2
=15x²-13x+20