Toán Lớp 8: Bài 2.Tìm x a) (2x+2)(4x^2-4x+4)-2x(4x^2-2)=15 b) 2x(2x-5)(2x+5)-(2x+2)(4x^2-4x+4)=3 giải gấp ạ

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Toán Lớp 8:  Bài 2.Tìm x a) (2x+2)(4x^2-4x+4)-2x(4x^2-2)=15 b) 2x(2x-5)(2x+5)-(2x+2)(4x^2-4x+4)=3 giải gấp ạ

daolanhoa · Answer

#Sad   a)   (2x+2)(4x^2-4x+4)-2x(4x^2-2) = 15   &hArr; 8x^3+8-8x^3+4x-15 = 0   &hArr; 4x-7 = 0   &hArr; 4x = 7   &hArr; x = 7/4    text{Vậy S=} {7/4}   b)   2x(2x-5)(2x+5)-(2x+2)(4x^2-4x+4) = 3   &hArr; 2x(4x^2-25)-8x^3-8-3 = 0   &hArr; 8x^3-50x-8x^3-11 = 0   &hArr; -50x = 11   &hArr; x = -(11)/(50)    text{Vậy S=} {-(11)/(50)}

mytamhoang · Answer

B&agrave;i 2.T&igrave;m x:   a)(2x+2).(4x&sup2;-4x+4)-2x.(4x&sup2;-2)=15   &hArr;8x&sup3;+8-8x&sup3;+4x=15   &hArr;8x&sup3;+8-8x&sup3;+4x-15=0   &hArr;4x-7=0   &hArr;x=$ frac{7}{4}$   Vậy x= $ frac{7}{4}$   b)2x.(2x-5).(2x+5)-(2x+2).(4x&sup2;-4x+4)=3   &hArr;2x.(4x&sup2;-25)-(8x&sup3;+8)=3   &hArr;8x&sup3;-50x-8x&sup3;-8-3=0   &hArr;-50x-11=0   &hArr;x=$ frac{-11}{50}$   Vậy x= $ frac{-11}{50}$   ~ ch&uacute;c tus học tốt nha!!!~