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

Toán Lớp 8: tìm x (x-3)(x+1)=8 tính 9999+10001

Toán Lớp 8: tìm x
(x-3)(x+1)=8
tính
9999+10001

Comments ( 2 )

  1. Giải đáp:
    (x-3)(x+1)=8
    <=> x^2 – 2x -3 – 8 = 0
    <=> x^2 – 2x -11 = 0
    <=> (x^2 – 2x +1 )- 12= 0
    <=> ( x -1)^2 – 12 = 0
    <=> ( x -1 – \sqrt{12})(x-1 + \sqrt{12} ) = 0
    <=> $\left[\begin{matrix} x=1 + 2 \sqrt{3}\\ x=1 – 2\sqrt{3}\end{matrix}\right.$
    $\\$
    9999 + 10001
    = 9999 + 1 + 10000
    = 10000+ 10000
    = 20000

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