Toán Lớp 8: Tìm x biết: G, 2x³-50x=0 H, 2x(3x-5)-(5-3x)=0

Question

Toán Lớp 8:  Tìm x biết: G, 2x³-50x=0 H, 2x(3x-5)-(5-3x)=0

dananhnhu2k4 · Answer

Giải đáp:       Lời giải và giải thích chi tiết:    2x&sup3;-50x=0     &hArr;x(2x-50)=0     &hArr; ( left[  begin{array}{l}x=0  x=2x-50=0 end{array}  right. )      &hArr; ( left[  begin{array}{l}x=0  x=25 end{array}  right. )      h)2x(3x-5)-(5-3x)=0     &hArr;2x(3x-5)-(3x-5)=0     &hArr;(3x-5)(2x-1)=0     &hArr; ( left[  begin{array}{l}3x-5=0  -2x-1=0 end{array}  right. )      &hArr; ( left[  begin{array}{l}x= dfrac{5}{3}  x=- dfrac{1}{2} end{array}  right. )

catlantuong · Answer

g) 2x^3-50x=0   &hArr;2x(x^2-25)=0   &hArr;2x(x-5)(x+5)=0   &hArr; ( left[  begin{array}{l}2x=0  x-5=0  x+5=0 end{array}  right. )    &hArr; ( left[  begin{array}{l}x=0  x=5  x=-5 end{array}  right. )    Vậy S={0,5,-5}   h) 2x(3x-5)-(5-3x)=0   &hArr;2x(3x-5)+(3x-5)=0   &hArr;(3x-5)(2x+1)=0   &hArr; ( left[  begin{array}{l}3x-5=0  2x+1=0 end{array}  right. )    &hArr; ( left[  begin{array}{l}x= dfrac{5}{3}  x=- dfrac{1}{2} end{array}  right. )    Vậy S={5/3,-1/2}