tìm x thõa mãn: a) x+5/95 + x+10/90 + x+15/85 + x+20/80 = -4 b) x-13/87 + x-27/73 + x-67/33 + x-73/27 = 4 làm ơn giúp em với ạ. mai em kiểm tra

$\text{a) $\dfrac{x + 5}{95}$ + $\dfrac{x + 10}{90}$ + $\dfrac{x + 15}{85}$ + $\dfrac{x + 20}{80}$ = -4}$

$\text{$\dfrac{x + 5}{95}$ + $\dfrac{x + 10}{90}$ + $\dfrac{x + 15}{85}$ + $\dfrac{x + 20}{80}$ + 4 = -4 + 4}$

$\text{($\dfrac{x + 5}{95}$ + 1) + ($\dfrac{x + 10}{90}$ + 1) + ($\dfrac{x + 15}{85}$ + 1) + ($\dfrac{x + 20}{80}$ + 1) = 0}$

$\text{$\dfrac{x + 5 + 95}{95}$ + $\dfrac{x + 10 + 90}{90}$ + $\dfrac{x + 15 + 85}{85}$ + $\dfrac{x + 20 + 80}{80}$ = 0}$

$\text{$\dfrac{x + 100}{95}$ + $\dfrac{x + 100}{90}$ + $\dfrac{x + 100}{85}$ + $\dfrac{x +100}{80}$ = 0}$

$\text{(x + 100)($\dfrac{1}{95}$ + $\dfrac{1}{90}$ + $\dfrac{1}{85}$ + $\dfrac{1}{80}$) = 0}$

$\text{x + 100 = 0 : ($\dfrac{1}{95}$ + $\dfrac{1}{90}$ + $\dfrac{1}{85}$ + $\dfrac{1}{80}$)}$

$\text{x + 100 = 0}$

$\text{x = -100}$

$\text{Vậy x = -100}$

$\text{b) $\dfrac{x - 13}{87}$ + $\dfrac{x - 27}{73}$ + $\dfrac{x - 67}{33}$ + $\dfrac{x - 73}{27}$ = 4}$

$\text{$\dfrac{x - 13}{87}$ + $\dfrac{x - 27}{73}$ + $\dfrac{x - 67}{33}$ + $\dfrac{x - 73}{27}$ - 4 = 4 - 4}$

$\text{($\dfrac{x - 13}{87}$ - 1) + ($\dfrac{x - 27}{73}$ - 1) + ($\dfrac{x - 67}{33}$ - 1) + ($\dfrac{x - 73}{27}$ - 1) = 4 -4}$

$\text{$\dfrac{x - 13 - 87}{87}$ + $\dfrac{x - 27 - 73}{73}$ + $\dfrac{x - 67 - 33}{33}$ + $\dfrac{x - 73 - 27}{27}$ = 0}$

$\text{$\dfrac{x - 100}{87}$ + $\dfrac{x - 100}{73}$ + $\dfrac{x - 100}{33}$ + $\dfrac{x - 100}{27}$ = 0}$

$\text{(x - 100)($\dfrac{1}{87}$ + $\dfrac{1}{73}$ + $\dfrac{1}{33}$ + $\dfrac{1}{27}$) = 0}$

$\text{x - 100 = 0 : ($\dfrac{1}{87}$ + $\dfrac{1}{73}$ + $\dfrac{1}{33}$ + $\dfrac{1}{27}$)}$

$\text{x - 100 = 0}$

$\text{x = 100}$

$\text{Vậy x = 100}$

$\textit{Ha1zzz}$