Bạn tham khảo nhé
a) $\frac{x-342}{15}$ + $\frac{x-323}{17}$ + $\frac{x-300}{19}$ + $\frac{x-272}{21}$ = 0
<=> $\frac{2261(x-342)}{33915}$ + $\frac{1995(x - 323)}{33915}$ + $\frac{1785(x-300)}{33915}$ + $\frac{1615(x - 272)}{33915}$ = 0
=> 2261(x - 342) + 1995(x - 323) + 1785(x - 300) + 1615(x - 272) = 0
<=> 2261x - 773262 + 1995x - 644385 + 1785x - 535500 + 1615x - 439280 = 0
<=> 7656x - 2392427 = 0
<=> 7656x = 2392427
<=> x ≈ 312,49
Vậy x ≈ 312,49
b) $\frac{x+1}{15}$ + $\frac{x+2}{7}$ + $\frac{x+4}{4}$ + 7 = 0
<=>$\frac{28(x+1)}{420}$ +$\frac{60(x+2)}{420}$ + $\frac{105(x+4)}{420}$ + $\frac{420.7}{420}$ = 0
=> 28(x + 1) + 60(x + 2) + 105(x + 4) + 2940 = 0
<=> 28x + 28 + 60x + 120 + 105x + 420 + 2940 = 0
<=> 193x + 3508 = 0
<=> 193x = -3508
<=> x = -$\frac{3508}{193}$
Vậy x = -$\frac{3508}{193}$
