\(c,\left(x+1\right)\left(x+9\right)=\left(x+3\right)\left(x+5\right)\\ \Rightarrow x^2+x+9x+9=x^2+3x+5x+15\\ \Rightarrow x^2+10x+9=x^2+8x+15\\ \Rightarrow x^2+10x+9-x^2-8x-15=0\\ \Rightarrow2x-6=0\\ \Rightarrow x=3\)
\(d,\left(3x+5\right)\left(2x+1\right)=\left(6x-2\right)\left(x-3\right)\\ \Rightarrow6x^2+10x+3x+5=6x^2-2x-18x+6\\ \Rightarrow6x^2+13x+5=6x^2-20x+6\\ \Rightarrow6x^2+13x+5-6x^2+20x-6=0\\ \Rightarrow33x-1=0\\ \Rightarrow x=\dfrac{1}{33}\)
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