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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: tìm x ; y a,(x^3 – 3x^2 + x – 3) : ( x – 3) – x^2 + x = 0 b,f) x^2+y^2-6x+6y+18=0

Toán Lớp 8: tìm x ; y
a,(x^3 – 3x^2 + x – 3) : ( x – 3) – x^2 + x = 0
b,f) x^2+y^2-6x+6y+18=0

Comments ( 1 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
    a) (x^3 – 3x^2 + x – 3) : (x – 3) – x^2 + x = 0
    <=> [x^2 . (x – 3) + (x – 3)] : (x – 3) – x^2 + x = 0
    <=> [(x^2 + 1) . (x – 3)] : (x – 3) – x^2 + x = 0
    <=> (x^2 + 1) – x^2 + x = 0
    <=> x^2 + 1 – x^2 + x = 0
    <=> x + 1 = 0
    <=> x = -1
    Vậy x = -1
    b) x^2 + y^2 – 6x – 6y + 18 = 0 (sửa đề)
    <=> (x^2 – 6x + 9) + (y^2 – 6y + 9) = 0
    <=> (x – 3)^2 + (y – 3)^2 = 0
    <=> $\begin{cases} (x – 3)^2 = 0\\(y – 3)^2 = 0 \end{cases}$
    <=> $\begin{cases} x – 3 = 0\\y – 3 = 0 \end{cases}$
    <=> $\begin{cases} x = 3\\y = 3 \end{cases}$
    Vậy $\begin{cases} x = 3\\y = 3 \end{cases}$
    *B

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222-9+11+12:2*14+14 = ? ( )

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