Toán Lớp 8: Tính x/x-2 – 2x/x-2*x+6/2x^2+4x
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Toán Lớp 8: Tính x/x-2 – 2x/x-2*x+6/2x^2+4x
Comments ( 2 )
Giải đáp:
= – {2x^3 + 3x^2 – 4x + 12}/{2x(x + 2)(x – 2)}
Lời giải và giải thích chi tiết:
x/{x – 2} – {2x}/{x – 2} + {x + 6}/{2x^2 + 4x}
= x/{x – 2} – {2x}/{x – 2} + {x + 6}/{2x(x + 2)}
= {x . 2x(x + 2)}/{2x(x + 2)(x – 2)} – {2x . 2x(x + 2)}/{2x(x + 2)(x – 2)} + {(x + 6)(x – 2)}/{2x(x + 2)(x – 2)}
= {2x^2 (x + 2)}/{2x(x + 2)(x – 2)} – {4x^2(x + 2)}/{2x(x + 2)(x – 2)} + {x^2 – 2x + 6x – 12}/{2x(x + 2)(x – 2)}
= {2x^3 + 4x^2}/{2x(x + 2)(x – 2)} – {4x^3 + 8x^2}/{2x(x + 2)(x – 2)} + {x^2 + 4x – 12}/{2x(x + 2)(x – 2)}
= {2x^3 + 4x^2 – (4x^3 + 8x^2) + x^2 + 4x – 12}/{2x(x + 2)(x – 2)}
= {2x^3 + 4x^2 – 4x^3 – 8x^2 + x^2 + 4x – 12}/{2x(x + 2)(x – 2)}
= {(2x^3 – 4x^3) – (8x^2 – 4x^2 – x^2) + 4x – 12}/{2x(x + 2)(x – 2)}
= {- 2x^3 – 3x^2 + 4x – 12}/{2x(x + 2)(x – 2)}
= – {2x^3 + 3x^2 – 4x + 12}/{2x(x + 2)(x – 2)}
#SunHee
Giải đáp+Lời giải và giải thích chi tiết:
x/(x-2)-(2x)/(x-2). (x+6)/(2x^2+4x)
=x/(x-2)-(2x)/(x-2).(x+6)/[2x(x+2)]
=x/(x-2)-[2x(x+6)]/[2x(x+2)(x-2)]
=x/(x-2)-(x+6)/[(x+2)(x-2)]
=[x(x+2)]/[(x+2)(x-2)]-(x+6)/[(x+2)(x-2)]
=(x^2+2x-x-6)/[(x+2)(x-2)]
=(x^2+x-6)/[(x+2)(x-2)]
=(x^2-2x+3x-6)/[(x+2)(x-2)]
=[x(x-2)+3(x-2)]/[(x+2)(x-2)]
=[(x+3)(x-2)]/[(x+2)(x-2)]
=(x+3)/(x+2)