Nhớ Vote nha mọi người !Đk: x≥13Ta có: pt⟺9x2−9x−10x2−4x+7=x√3x−1−2x⟺(3x−5)(3x+2)x2−4x+7=x(3x−5)√3x−1+2⟺x=53.v.3x+2x2−4x+7=x√3x−1+2(1)pt(1)⟺(3x+2)√3x−1+2(3x+2)=x(x2−4x+7)⟺(3x+2)√3x−1=x3−4x2+x−4⟺x3−4x2+x−4−(3x+2)√3x−1=0⟺x3−4x2+x−4−(3x+2)(x−2)+(3x+2)(x−2−√3x−1)=0⟺x3−7x2+5x+(3x+2)(x−2−√3x−1)=0⟺x(x−2−√3x−1)(x−2+√3x−1)+(3x+2)(x−2−√3x−1)=0⟺(x−2−√3x−1)[x2−2x+x√3x−1+3x+2]=0⟺(x−2−√3x−1)[x2+x+2+x√3x−1]=0Do x≥13 nên [...]>0Suy ra x−2−√3x−1=0⟺(x−2)2=3x−1⟺x2−7x+5=0⟺x=7+√292.v.x=7−√292Bạn tự KL nhé. Nhớ Vote! và chấm đúng nha!
Nhớ Vote nha mọi người !Đk:
x≥13Ta có:
pt⟺9x2−9x−10x2−4x+7=x√3x−1−2x⟺(3x−5)(3x+2)x2−4x+7=x(3x−5)√3x−1+2⟺x=53.v.3x+2x2−4x+7=x√3x−1+2(1)pt(1)⟺(3x+2)√3x−1+2(3x+2)=x(x2−4x+7)⟺(3x+2)√3x−1=x3−4x2+x−4⟺x3−4x2+x−4−(3x+2)√3x−1=0⟺x3−4x2+x−4−(3x+2)(x−2)+(3x+2)(x−2−√3x−1)=0⟺x3−7x2+5x+(3x+2)(x−2−√3x−1)=0⟺x(x−2−√3x−1)(x−2+√3x−1)+(3x+2)(x−2−√3x−1)=0⟺(x−2−√3x−1)[x2−2x+x√3x−1+3x+2]=0⟺(x−2−√3x−1)[x2+x+2+x√3x−1]=0Do
x≥13 nên
[...]>0Suy ra
x−2−√3x−1=0⟺(x−2)2=3x−1⟺x2−7x+5=0(x>=2)$\iff x=\frac{7+\sqrt{29}}{2}.v.x=\frac{7-\sqrt{29}}{2}
(l)$Bạn tự KL nhé. Nhớ Vote! và chấm đúng nha!