tim x biet |x-3|+|x+2|=7
TIM X BIET(X-2)^3-X^3+6X^2=7
giải hằng đẳng thức rồi rút gọn tìm x nhé
tim x biet;(x-2)^3-x^3+6x^2=7
<=>x^3-6x^2+12x-8-x^3+6x^2=7
<=>12x=15
<=> x=5/4
chúc bạn hk tốt
tim x biet: a) |x+2| - 6x=7 b) |x-3|+|x+2|=7
tim x biet x^2*(x-2)+x*(-3+2x)-5x=7
\(x^2\left(x-2\right)+x\left(-3+2x\right)-5x=7\)
\(x^3-2x^2-3x+2x^2-5x=7\)
\(x^3-8x-7=0\)
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!!
tim x biet 2.(x-5)-3.(x+7)=14
2.(x-5)-3.(x+7)=14
-> 2x-10-3x-21=14
->-x-31=14
->-x=45
->x=-45
tim x biet (x^2-1)(x^2-3)(x^2-5)(x^2-7)<=0
tim x biet :
-x-2/3=-6/7
4/7-x=1/3
-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
tim x biet
2(x-5)-3(x+7)=14
2.(x - 5) - 3.(x + 7) = 14
=> 2x - 10 - 3x - 21 = 14
=> -x = 14 + 21 + 10
=> -x = 45
=> x = -45
tim x biet
(3.x-5)-(2.x-7)=0
Vì (3.x-5)-(2.x-7)=0 nên 3.x-5=2.x-7( vì 2 số bằng nhau trừ cho nhau bằng 0)
Có 3.x-5=2.x-7 ( bên dưới mình áp dụng quy tắc chuyển vế nhé)
3.x-2.x=5-7
x=-2
Tick cho mình nhé. Chắc chắn đúng