Question

a) ( x+3 ) * ( x^2 - 3x +9 ) - ( 54+ x^3 )

b) ( 2x + y ) * ( 4x^2 - 2xy + y^2 ) - ( 2x - y ) * ( 4x^2 + 2xy + y^2 )

c) ( a+b ) ^3 - ( a-b ) ^3 - 2b^3

d) ( x+y+z ) ^ 2 - 2 * ( x+y+z ) * ( x+y ) + y^2 + ( x + y ) ^ 2

Answer 1

cái đề là rút gọn các biểu thức nha

Answer 2

Tự làm đi dễ mà

Answer 3

a) \(\left(x+3\right)\left(x^2-3x+9\right)-\left(54+x^3\right)\)

\(=x^3+27-54-x^3\)

\(=-27\)

b) \(\left(2x+y\right)\left(4x^2-2xy+y^2\right)-\left(2x-y\right)\left(4x^2+2xy+y^2\right)\)

\(=\left(8x^3+y^3\right)-\left(8x^3-y^3\right)\)

\(=8x^3+y^3-8x^3+y^3\)

\(=2y^3\)

c) \(\left(a+b\right)^3-\left(a-b\right)^3-2b^3\)

\(=\left[\left(a+b\right)-\left(a-b\right)\right]\left[\left(a+b\right)^2+\left(a+b\right)\left(a-b\right)-\left(a-b\right)^2\right]-2b^3\)

\(=\left(a+b-a+b\right)\left[\left(a^2+2ab+b^2\right)+\left(a^2-ab+ab-b^2\right)-\left(a^2-2ab+b^2\right)\right]-2b^3\)

\(=b^2\left(a^2+2ab+b^2+a^2-ab+ab-b^2-a^2+2ab-b^2\right)-2b^3\)

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