bằng 2

= 2 nha!!

a2021

b2023

A. 1997 + 24 = (1997 + 3) + (24 - 3)

                      = 2000 + 21

                      = 2021

B. 29 + 1994 = (29 - 6) + (1994 + 6)

                     =  23 + 2000

                     = 2023

viết dưới dạng số thập phân hộ mk 

Trl :

216 cm ; 345 cm ; 48 m ; 15,4 dam 

495,4 m ; 120,6 ; 452170 m ; 8 mm 

147 mm

HokT~

\(\sqrt{x-3}-2\ne0\)

\(\sqrt{x-3}\ne2\)

\(x\ne7\left(1\right)\)

\(\sqrt{x-3}\ge0\)

\(x\ge3\left(2\right)\)

\(\left(1\right);\left(2\right)< =>x\ge3;x\ne7\)

x>=3; x khác 7 

9 nha hok tốt

9 nha bn 

Hok tốt ^^

\(15.a,\sqrt{3}\left(\sqrt{4}+2\sqrt{9}\right)\frac{\sqrt{3}}{2}-\sqrt{150}\)

\(\left(2+2.3\right)\frac{3}{2}-\sqrt{150}\)

\(12-\sqrt{150}\)

\(6\left(2-\sqrt{25}\right)=6\left(-3\right)=-18\)

\(b,\left(\sqrt{28}-\sqrt{12}-\sqrt{7}\right).\sqrt{7}+2\sqrt{21}\)

\(\sqrt{196}-\sqrt{84}-7+2\sqrt{21}\)

\(14-\sqrt{21}\left(\sqrt{4}+2\right)-7\)

\(7-\sqrt{21}.4\)

\(7-\sqrt{84}\)

\(c,\left(1+\sqrt{2}-\sqrt{3}\right)\left(1+\sqrt{2}+\sqrt{3}\right)\)

\(1+\sqrt{2}-\sqrt{3}+\sqrt{2}+2-\sqrt{6}+\sqrt{3}+\sqrt{6}-3\)

\(=2\sqrt{2}\)

\(d,\sqrt{3}\left(\sqrt{2}-\sqrt{3}\right)^2-\sqrt{3}+\sqrt{2}\)

\(\sqrt{3}\left(2-\sqrt{6}+3\right)-\sqrt{3}+\sqrt{2}\)

\(\sqrt{3}\left(5-\sqrt{6}-1\right)+\sqrt{2}\)

\(\sqrt{3}\left(4-\sqrt{6}\right)+\sqrt{2}\)

\(4\sqrt{3}-\sqrt{18}+\sqrt{2}\)

\(\sqrt{2}\left(2\sqrt{3}-3+1\right)\)

\(\sqrt{2}\left(2\sqrt{3}-2\right)\)

\(2\sqrt{6}-\sqrt{6}=\sqrt{6}\)

M=1-1/2-1/4-1/8-...-1/2048

=1-(1/2+1/4+...+1/2048)

=1-(1-1/2048)

=1/2048

Theo đề ra, ta có:

\(\frac{y}{2}\)

\(\Leftrightarrow2x+3y=8\)

\(\Leftrightarrow2\left(\frac{y}{2}\right)+3y=8\)

\(\Leftrightarrow y+3y=8\)

\(\Leftrightarrow4y=8\)

\(\Leftrightarrow y=2\Rightarrow x=1\)

\(\Leftrightarrow\frac{3}{4}x^6y^7=\frac{3}{4}.1.2^7=96\)