Gui ban Ha Nhien 4 cach

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x — x Lời giải: Nguyễn + - 20x Đăng Khoa & Nguyễn Đức Tân ĐKXD:x>0 Cl: x-x+2— 24x =0 & x(x —1)—2(vx —1)=0 x(x—l)-2 2-1 ~0 Vx +1 ote ofx- : =0 Vx +1 Néu x(Vvx +1) =2: ——— =xk(GT) ox EEE? =2 ©x'-x +4x-4=0 & (x—D(x’* +4) =0 >x=1 Vậy x=l C2: x—x+2—24x —=x —-x+2—-241x>x”-x+2-(x+l)=(x-!} Dấu "=" xảy x=l Vậy x=l >0 C3: Dat Vx =a(a>0) >a‘ —a’+2-—2a=0 a*—a’ +a —a° —2(a—l1l)=0 < (a—1)(a* +a’ —2)=0 © (a—I)(—a” +2a”—2)=0 ©(a—-IJƒ(aˆ+2a+2)=0 >a=l1>x=1l C4:x”—x+2—2Ax =0 & (x? —x+2)° =4x & xt +x*° +4—2x* +4x* —4x =4x & xt —2x° +5x* —8x +4=0 & xt—x? —x? +x? +4x° —4x—4x+4=0 & (x —1)(x*? —x* +4x—4) =0 & (x —1)’°(x* +4) =0 >x=1 ... ©(a—-IJƒ(aˆ+2a+2)=0 >a=l1>x=1l C4:x”—x+2—2Ax =0 & (x? —x+2)° =4x & xt +x*° +4? ??2x* +4x* —4x =4x & xt —2x° +5x* —8x +4= 0 & xt—x? —x? +x? +4x° —4x—4x +4= 0 & (x —1)(x*? —x* +4x? ?4) =0 & (x —1)’°(x* +4) =0 >x=1