Toán Tìm x trong các tỉ lệ thức sau: c) $\dfrac{x-1}{x-5}$ = $\dfrac{6}{7}$ d) $\dfrac{x^2}{6}$ $=$ $\dfrac{24}{25}$ e) $\dfrac{x-2}{x-1}$ $=$ $\dfrac{x+4 18/07/2021 By Savannah Tìm x trong các tỉ lệ thức sau: c) $\dfrac{x-1}{x-5}$ = $\dfrac{6}{7}$ d) $\dfrac{x^2}{6}$ $=$ $\dfrac{24}{25}$ e) $\dfrac{x-2}{x-1}$ $=$ $\dfrac{x+4}{x+7}$
c) `(x-1)/(x-5)=6/7` `→7(x-1)=6(x-5)` `→7x-7=6x-30` `→7x-6x=-30+7` `→x=-23` d) `x^2/6=24/25` `→x^2=24/25 . 6` `→x^2=144/25` `→x=±12/5` e) `(x-2)/(x-1)=(x+4)/(x+7)` `→(x-2)(x+7)=(x+4)(x-1)` `→x^2-2x+7x-14=x^2+4x-x-4` `→x^2+5x-14=x^2+3x-4` `→x^2-x^2+5x-3x=-4+14` `→2x=10` `→x=5` Trả lời