phương trình lượng giác

0

01697981687

6sin^2x+4cos^2x=6sinx+4cosx
<=>(24tan^2(x/2))/(1+tan^2(x/2))^2+(4(1-tan^2x/2))/(1+tan^2x/2)^2=(12tanx/2)/(1+tan^2x/2)+(4(1-tan^2x/2))/(1+tan^2x/2)
<=>24tan^2x/2+4-4tan^2x/2=12tanx/2+12tan^3x/2+4-4tan^4x/2
<=>4tan^4x/2-12tan^3x/2+20tan^2x/2-12tanx/2=0
ok nhé
 
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