(x+5)^10+(10+2x)^20
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a. $(-20)+x=-30$
$x-20=-30$
$x=-30+20=-(30-20)=-10$
b.
$(-10)-x=-20$
$x=(-10)-(-20)=-10+20=20-10=10$
c. Đề sai. Bạn xem lại.
d.
$x+(-3)=-7$
$x=-7-(-3)=-7+3=-(7-3)=-4$
e.
$x-(-5)=-9$
$x=(-9)+(-5)=-14$
f.
$x(-11)=12$
$x=\frac{12}{-11}=\frac{-12}{11}$
h.
$2x-10=20$
$2x=20+10=30$
$x=30:2=15$
l.
$4x-8=-8$
$4x=-8+8=0$
$x=0:4=0$
k.
$-12-(-2)x=-8$
$(-2)x=-12-(-8)=-12+8=-(12-8)=-4$
$x=(-4):(-2)=2$
Bài 2:
a. $-20-(10-x)=-3$
$10-x=-20-(-3)=-20+3=-(20-3)=-17$
$x=10-(-17)=10+17=27$
b.
$14+(14-x)=-2$
$14-x=-2-14=-16$
$x=14-(-16)=14+16=30$
c.
$-15-(x-3)=-7$
$x-3=-15-(-7)=-15+7=-8$
x=-8+3=-5$
d.
$(x+4)+(-20)=-8$
$x+4=-8-(-20)=-8+20=12$
$x=12-4=8$
e.
$-2x-2=-4$
$-2x=-4+2=-2$
$x=(-2):(-2)=1$
f.
$-2x+4=-4$
$-2x=-4-4=-8$
$x=(-8):(-2)=4$
l.
$-12-(-2)x=-2-4=-6$
$(-2)x=-12-(-6)=-12+6=-6$
$x=(-6):(-2)=3$
![](https://rs.olm.vn/images/avt/0.png?1311)
a) x = 2.
b) x = 7.
c) x= 12.
d) x= 45.
e) x = 18.
f) x = 10.
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-4\left(x-10\right)+5=-2x-\left(x+7\right)-\left(-20+8\right)\)
\(\Leftrightarrow-4x+40+5=-2x-x-7+20-8\)
\(\Leftrightarrow-4x+2x+x=-40-5-7-20-8\)
\(\Leftrightarrow-x=-80\)
\(\Leftrightarrow x=80\)
Vậy...
−4(x−10)+5=−2x−(x+7)−(−20+8)−4(x−10)+5=−2x−(x+7)−(−20+8)
⇔−4x+40+5=−2x−x−7+20−8⇔−4x+40+5=−2x−x−7+20−8
⇔−4x+2x+x=−40−5−7−20−8⇔−4x+2x+x=−40−5−7−20−8
⇔−x=−80⇔−x=−80
⇔x=80⇔x=80
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{x-5}{x+2}-\dfrac{10}{x}-\dfrac{20}{x^2+2x}\)
\(=\dfrac{x\left(x-5\right)-10\left(x+2\right)-20}{x\left(x+2\right)}\)
\(=\dfrac{x^2-5x-10x-20-20}{x\left(x+2\right)}\)
\(=\dfrac{x^2-15x-40}{x\left(x+2\right)}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(240-\left(x+5\right)=137\)
\(x+5=240-137\)
\(x+5=103\)
\(x=103-5=98\)
b) \(\left(2x-10\right)-20=110\)
\(2x-10=110+20\)
\(2x-10=130\)
\(2x=130+10\)
\(2x=140\)
\(x=140:2=70\)
\(a,240-\left(x+5\right)=137\\ x+5=103\\ x=98\\ b,\left(2x-10\right)-20=110\\ 2x-10=130\\ 2x=140\\ x=70\)