Answer:
Step-by-step explanation:
13.
x³-x²-x-2=0
x³-2x²+x^2-2x+x-2=0
x²(x-2)+x(x-2)+1(x-2)=0
(x-2)(x²+x+1)=0
x-2=0,x=2
x²+x+1=0
<em>12.</em>
<em>3x^4-11x³+15x²-9x+2=0</em>
<em>\[3x^4-3x^3-8x^3+8x²+7x²-7x-2x+2=0\]</em>
<em>3x³(x-1)-8x²(x-1)+7x(x-1)-2(x-1)=0</em>
<em>(x-1)[3x³-8x²+7x-2]=0</em>
<em>x-1=0,gives x=1</em>
<em>3x³-8x²+7x-2=0</em>
<em>3x³-3x²-5x²+5x+2x-2=0</em>
<em>3x²(x-1)-5x(x-1)+2(x-1)=0</em>
<em>(x-1)(3x²-5x+2)=0</em>
<em>x-1=0,gives x=1</em>
<em>3x²-5x+2=0</em>
<em>3x²-3x-2x+2=0</em>
<em>3x(x-1)-2(x-1)=0</em>
<em>(x-1)(3x-2)=0</em>
<em>x-1=0,gives x=1</em>
<em>3x-2=0, gives x=2/3</em>
<em>so roots are 2/3,1,1,1</em>
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