-x-2/3=-6/7

=>-x=-6/7+(-2/3)

=>-x=-32/21

=>x=32/21

4/7-x=1/3

=>x=4/7-1/3

=>x=5/21

-x-2/3=-6/7

=>-x=-6/7+(-2/3)

=>-x=-32/21

=>x=32/21

4/7-x=1/3

=>x=4/7-1/3

=>x=5/21

giải hằng đẳng thức rồi rút gọn tìm x nhé

<=>x^3-6x^2+12x-8-x^3+6x^2=7

<=>12x=15

<=> x=5/4

chúc bạn hk tốt

dễ quá mà

2.(x-5)-3.(x+7)=14

-> 2x-10-3x-21=14

->-x-31=14

->-x=45

->x=-45

x=-45 nhé

là 45 nhé bạn

-2 tick nhé Tran Thi Xuan

\(x^2\left(x-2\right)+x\left(-3+2x\right)-5x=7\)

\(x^3-2x^2-3x+2x^2-5x=7\)

\(x^3-8x-7=0\)

lam the nao nua

lm tiếp như sau nha bn!!

\(x^3-8x-7=0\)

\(\Leftrightarrow x^3-x^2+x^2-x-7x-7=0\)

\(\Leftrightarrow x^2\left(x-1\right)+x\left(x-1\right)-7\left(x+1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(x^2+x\right)-7\left(x+1\right)=0\)

\(\Leftrightarrow x\left(x-1\right)\left(x+1\right)-7\left(x+1\right)=0\)

\(\Leftrightarrow\left(x+1\right)\left[x\left(x-1\right)-7\right]=0\)

\(\Leftrightarrow\left(x+1\right)\left(x^2-x-7\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x+1=0\\x^2-x-7=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-1\\x^2-x-7=0\left(1\right)\end{cases}}}\)

Nếu bn hok sang kì II lp 9 thì (1) lm tiếp như sau:

\(x^2-x-7=0\)

\(\Delta=\left(-1\right)^2-4.1.\left(-7\right)=29>0\)

\(\Rightarrow x_1=\frac{1+\sqrt{29}}{2}\)

\(x_2=\frac{1-\sqrt{29}}{2}\)

=.= hok tốt!!