Toán Lớp 7: Rút gọn
8$\bigg(x – \dfrac{1}{2}\bigg)$$\bigg(x^2+\dfrac{1}{2}x+\dfrac{1}{4}\bigg)$ – $4x^{}$$(1-x+2x^2)^{}$
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Toán Lớp 7: Rút gọn
8$\bigg(x – \dfrac{1}{2}\bigg)$$\bigg(x^2+\dfrac{1}{2}x+\dfrac{1}{4}\bigg)$ – $4x^{}$$(1-x+2x^2)^{}$
Comments ( 2 )
=8.[x.(x^2+1/2x+1/4)-1/2.(x^2+1/2x+1/4)]-(4x.1-4x.x+4x.2x^2)
=8.(x^3+1/2x^2+1/4x-1/2x^2-1/4x-1/8)-(4x-4x^2+8x^3)
=8.[x^3+(1/2x^2-1/2x^2)+(1/4x-1/4x)-1/8]-4x+4x^2-8x^3
=8.(x^3-1/8)-4x+4x^2-8x^3
=8x^3-8 . 1/8-4x+4x^2-8x^3
=8x^3 – 1-4x+4x^2-8x^3
=(8x^3-8x^3)+4x^2-4x-1
=4x^2-4x-1