$\frac{x-941}{41}$ + $\frac{x-931}{31}$ + $\frac{x-921}{21}$ = -3
⇔$\frac{x-941}{41}$ + $\frac{x-931}{31}$ + $\frac{x-921}{21}$ +3 = 0
⇔$\frac{x-941}{41}$ +1 + $\frac{x-931}{31}$ +1 + $\frac{x-921}{21}$ +1 = 0
⇔$\frac{x-941}{41}$ + $\frac{41}{41}$ + $\frac{x-931}{31}$ + $\frac{31}{31}$ + $\frac{x-921}{21}$ + $\frac{21}{21}$ = 0
⇔$\frac{x-941+41}{41}$ + $\frac{x-931+31}{31}$ + $\frac{x-921+21}{21}$ = 0
⇔$\frac{x-900}{41}$ + $\frac{x-900}{31}$ + $\frac{x-900}{21}$ = 0
⇔(x-900).($\frac{1}{41}$ + $\frac{1}{31}$ + $\frac{1}{21}$) = 0
Vì $\frac{1}{31}$ + $\frac{1}{21}$) $\neq$ 0
⇒ x-900=0⇔x=900
Vậy x=900
*Lm ơn vote vs cho mk xin ctlhn nhá. thks!
