Toán Lớp 8: tìm x,biết ; (x+2)^2 – x(x-3)= -10
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Toán Lớp 8: tìm x,biết ; (x+2)^2 – x(x-3)= -10
Comments ( 2 )
{(x + 2)^2} – x(x – 3) = – 10\\
\Leftrightarrow ({x^2} + 4x + 4) – ({x^2} – 3x) = – 10\\
\Leftrightarrow {x^2} + 4x + 4 – {x^2} + 3x = – 10\\
\Leftrightarrow 7x + 4 = – 10\\
\Leftrightarrow 7x = – 14\\
\Leftrightarrow x = – 2
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