665 bạn ạ chắc luôn

 123+877
=1000
Mình k bạn zùi đó k mình đi

123+877=1000

TA có

kết quả là:

123 + 877

= 1000

nha bn

\(-\left(-834+877+1045\right)+\left(-123-834+45\right)\\ =+834-877-1045+\left(-123\right)-834+45\\ =\left[+834+\left(-834\right)\right]-\left(877+123\right)-\left(1045-45\right)\\ =0-1000-1000\\ =-2000\)

123 + 877= 1000

1000 x 1=1000

0 + 1 = 1

123 + 877 = 1000

1000 x 1 = 1000

0 + 1 = 1

hi

1000

1000

1 

Ôi quá dễ !

a) x – 123 = 345                                                         b) x + 254 = 665

         x      = 345 + 123                                                    x          = 665 – 254

         x      =  468                                                                x       = 211

=7772

​=1476

​=1443

=7772

=1476

=1443

tck mình nha

= 7772

= 1476

= 1443

tk mk nha

b) \(\dfrac{16}{\sqrt{x-3}}+\dfrac{4}{\sqrt{y-1}}+\dfrac{1225}{\sqrt{z-665}}=82-\sqrt{x-3}-\sqrt{y-1}-\sqrt{z-665}\) (*)

Đk: \(\left\{{}\begin{matrix}x>3\\y>1\\z>665\end{matrix}\right.\)

(*) \(\Leftrightarrow\dfrac{16}{\sqrt{x-3}}+\dfrac{4}{\sqrt{y-1}}+\dfrac{1225}{\sqrt{z-665}}=82-\dfrac{x-3}{\sqrt{x-3}}-\dfrac{y-1}{\sqrt{y-1}}-\dfrac{z-665}{\sqrt{z-665}}\)

\(\Leftrightarrow\dfrac{16}{\sqrt{x-3}}+\dfrac{4}{\sqrt{y-1}}+\dfrac{1225}{\sqrt{z-665}}-82+\dfrac{x-3}{\sqrt{x-3}}+\dfrac{y-1}{\sqrt{y-1}}+\dfrac{z-665}{\sqrt{z-665}}=0\)

\(\Leftrightarrow\left(\dfrac{x-3}{\sqrt{x-3}}-\dfrac{8\sqrt{x-3}}{\sqrt{x-3}}+\dfrac{16}{\sqrt{x-3}}\right)+\left(\dfrac{y-1}{\sqrt{y-1}}-\dfrac{4\sqrt{y-1}}{\sqrt{y-1}}+\dfrac{4}{\sqrt{y-1}}\right)+\left(\dfrac{z-665}{\sqrt{z-665}}-\dfrac{70\sqrt{z-665}}{\sqrt{z-665}}+\dfrac{1225}{\sqrt{z-665}}\right)=0\)

\(\Leftrightarrow\dfrac{\left(\sqrt{x-3}-4\right)^2}{\sqrt{x-3}}+\dfrac{\left(\sqrt{y-1}-2\right)^2}{\sqrt{y-1}}+\dfrac{\left(\sqrt{z-665}-35\right)^2}{\sqrt{z-665}}=0\)

\(\Leftrightarrow\left\{{}\begin{matrix}\sqrt{x-3}-4=0\\\sqrt{y-1}-2=0\\\sqrt{z-665}-35=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=19\\y=5\\z=1890\end{matrix}\right.\)

Kl: x=19, y= 5, z=1890

c) \(\sqrt{x-5}-\dfrac{x-14}{3+\sqrt{x-5}}=3\) (*)

Đk: \(x\ge5\)

(*) \(\Leftrightarrow3\sqrt{x-5}+x-5-x+14=9+3\sqrt{x-5}\)

\(\Leftrightarrow0x=0\) (luôn đúng)

Vậy nghiệm của phương trình (*) là \(x\ge5\)

Chọn B

D

B

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