P = 5x(x2 – 3) + x2(7 – 5x) – 7×2 với x = – 5

Question

P = 5x(x2 – 3) + x2(7 – 5x) – 7×2 với x = – 5

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Kylie 1 tháng 2021-08-31T06:52:58+00:00 2 Answers 6 views 0

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    0
    2021-08-31T06:54:09+00:00

    `P=5x(x^2-3)+x^2(7-5x)-7x^2`

    `⇔P=5x^3-15x+7x^2-5x^3-7x^2`

    `⇔P=-15x`

    `⇔P=-15.(-5)`

    `⇔P=75`

    0
    2021-08-31T06:54:17+00:00

    $P(x)=5x(x^2-3)+x^2(7-5x)-7x^2$

    $= 5x^3-15x+7x^2-5x^3-7x^2$

    $= -15x$ 

    $\Rightarrow P(-5)=-15.(-5)=75$

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