Question

Giải nhanh , cần gấp ạ

 

Answer 1

7.

$(5+x)^2-36=0$

$(5+x)^2=36=6^2=(-6)^2$
$\Rightarrow 5+x=6$ hoặc $5+x=-6$

$\Rightarrow x=1$ hoặc $x=-11$

8.

$(7x-11)^3=2^5.5^2+200=1000=10^3$
$\Rightarrow 7x-11=10$

$\Rightarrow 7x=21$

$\Rightarrow x=3$

 

Answer 2

9.

$3^x+4^2=(8-3)^2=5^2$

$3^x=5^2-4^2=9=3^2$

$\Rightarrow x=2$

10.

$(2x-3)^3=27=3^3$

$\Rightarrow 2x-3=3$

$\Rightarrow 2x=6\Rightarrow x=3$

11.

$575-(6x+70)=445$

$6x+70=575-445=130$

$6x=130-70=60$

$x=60:6=10$
 

Answer 3

12.

$720:[41-(2x-5)]=2^3.5=40$

$41-(2x-5)=720:40=18$

$2x-5=41-18=23$
$2x=23+5=28$

$x=28:2=14$

13.

$2022^{x-2021}+3=(7-5)^2=4$

$2022^{x-2021}=4-3=1$

$\Rightarrow x-2021=0$

$\Rightarrow x=2021$

 

Answer 4

14.

$(x+1)+(x+2)+...+(x+30)=795$

$(x+x+...+x)+(1+2+...+30)=795$

$30x+465=795$
$30x=795-465=330$

$x=330:30=11$

15.

$[(x.x+55)-31].14=560$

$(x.x+55)-31=560:14=40$

$x.x+55=40+31=71$
$x.x=71-55=16=4.4=(-4)(-4)$

$\Rightarrow x=4$ hoặc $x=-4$