If the quotient and remainder obtained when the expression $3x^5-6x^4+2x^3+4x^2-5x+8$ is divided by the expression $x^2-2x+3$ are $ax^3+bx^2+cx+d$ and $px+q$ respectively, then $ab+cd =$
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For polynomial long division, be systematic. At each step, focus only on the leading terms of the current dividend and the divisor to find the next term of the quotient. Then multiply and subtract carefully.