dùng hdt để rút gọn (3x33x1).(3x3-3x1)-(3x1)2

Question

dùng hdt để rút gọn (3x^3+3x+1).(3x^3-3x+1)-(3x+1)^2

thanoanghha · Answer

(3x^3 + 3x + 1)(3x^3 - 3x + 1) - (3x + 1)^2   = (3x^3 + 1)^2 - (3x)^2 - (3x + 1)^2   = 9x^6 + 6x^3 + 1 - 9x^2 - 9x^2 - 6x - 1   = 9x^6 + 6x^3 - 18x^2 - 6x.   ________________   &Aacute;p dụng HĐT :   (1) : (A  + B)^2 = A^2 + 2AB + B^2   (3) : A^2 - B^2 = (A - B)(A + B)

hongocha12 · Answer

(3$x^{3}$ +3$x^{}$ +1).(3$x^{3}$ -3$x^{}$ +1)-(3$x^{}$ +1)&sup2;   = (3$x^{3}$ )&sup2; - (3$x^{}$ +1)&sup2; - (3$x^{}$ +1)&sup2;   = (3$x^{}$ +1)&sup2;. [(3$x^{3}$ )&sup2;-1]   = (3$x^{}$ +1)&sup2;. [(3$x^{3}$)&sup2; -1&sup2;]   = (3$x^{}$ +1)&sup2;. (3$x^{3}$+1) (3$x^{3}$-1)   = (9$x^{2}$+6$x^{}$+1) . (3$x^{6}$)-1   = 9$x^{6}$+6$x^{3}$-18$x^{2}$-6$x^{}$

dùng hdt để rút gọn (3x^3+3x+1).(3x^3-3x+1)-(3x+1)^2

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