a: \(10x^2-7x+a⋮2x-3\)
=>\(10x^2-15x+8x-12+a+12⋮2x-3\)
=>a+12=0
=>a=-12
b: \(2x^2+ax-4⋮x+4\)
=>\(2x^2+8x+\left(a-8\right)x+4\left(a-8\right)-4\left(a-8\right)-4⋮x+4\)
=>-4(a-8)-4=0
=>-4(a-8+1)=0
=>a-7=0
=>a=7
c: \(x^3+ax^2+5x+3⋮x^2+2x+3\)
=>\(x^3+2x^2+3x+\left(a-2\right)x^2+x\left(2a-4\right)+\left(3a-6\right)+\left(-2a+1+5\right)x+3-3a+6⋮x^2+2x+3\)
=>\(\left(-2a+6\right)x+9-3a⋮x^2+2x+3\)
=>\(\left\{{}\begin{matrix}-2a+6=0\\9-3a=0\end{matrix}\right.\)
=>a=3
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