phân tích thành nhân tử: a) $x^{4}$-5$x^{3}$+2$x^{2}$-$x^{1}$+3 b) $x^{3}$+3$x^{2}$-$x^{1}$-3 c) $x^{3}$+2$x^{2}$+4 $x^{1}$+3 d)6$x^{3}$-17$x^{2}$-

Question

phân tích thành nhân tử:
a) $x^{4}$-5$x^{3}$+2$x^{2}$-$x^{1}$+3
b) $x^{3}$+3$x^{2}$-$x^{1}$-3
c) $x^{3}$+2$x^{2}$+4 $x^{1}$+3
d)6$x^{3}$-17$x^{2}$-26$x^{1}$-3
e) $x^{4}$-3$x^{3}$+6$x^{2}$+13$x^{1}$+3

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Edana Edana 4 years 2020-10-17T02:00:19+00:00 1 Answers 86 views 0

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  1. Helga
    0
    2020-10-17T02:01:42+00:00
    Reply

    Giải thích các bước giải:

    $\begin{array}{l}
    a){x^4} – 5{x^3} + 2{x^2} – x + 3\\
     = \left( {{x^4} – {x^3}} \right) – \left( {4{x^3} – 4{x^2}} \right) – \left( {2{x^2} – 2x} \right) – \left( {3x – 3} \right)\\
     = \left( {x – 1} \right)\left( {{x^3} – 4{x^2} – 2x – 3} \right)\\
    b){x^3} + 3{x^2} – x – 3\\
     = \left( {{x^3} + 3{x^2}} \right) – \left( {x + 3} \right)\\
     = \left( {x + 3} \right)\left( {{x^2} – 1} \right)\\
     = \left( {x + 3} \right)\left( {x – 1} \right)\left( {x + 1} \right)\\
    c){x^3} + 2{x^2} + 4x + 3\\
     = \left( {{x^3} + {x^2}} \right) + \left( {{x^2} + x} \right) + \left( {3x + 3} \right)\\
     = \left( {x + 1} \right)\left( {{x^2} + x + 3} \right)\\
    d)6{x^3} – 17{x^2} – 26x – 3\\
     = \left( {6{x^3} + 6{x^2}} \right) – \left( {23{x^2} + 23x} \right) – \left( {3x + 3} \right)\\
     = \left( {x + 1} \right)\left( {6{x^2} – 23x – 3} \right)\\
    e){x^4} – 3{x^3} + 6{x^2} + 13x + 3\\
     = \left( {{x^4} + {x^3}} \right) – \left( {4{x^3} + 4{x^2}} \right) + \left( {10{x^2} + 10x} \right) + \left( {3x + 3} \right)\\
     = \left( {x + 1} \right)\left( {{x^3} – 4{x^2} + 10x + 3} \right)
    \end{array}$

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