Bài 11: Số vô tỉ. Khái niệm về căn bậc hai

1)

\(\sqrt{0,36}.\sqrt{\dfrac{25}{16}}+\left(-\dfrac{1}{2}\right)^2\)

\(=\dfrac{3}{5}.\dfrac{5}{4}+\dfrac{1}{4}\)

\(=\dfrac{3}{4}+\dfrac{1}{4}\)

\(=1\)

2)

\(\left(\dfrac{1}{4}-\dfrac{1}{\sqrt{64}}\right):\left(\dfrac{3}{2}\right)^2\)

\(=\left(\dfrac{1}{4}-\dfrac{1}{8}\right):\dfrac{9}{4}\)

\(=\left(\dfrac{2}{8}-\dfrac{1}{8}\right):\dfrac{9}{4}\)

\(=\dfrac{1}{8}:\dfrac{9}{4}\)

\(=\dfrac{1}{8}.\dfrac{4}{9}\)

\(=\dfrac{1}{18}\)

3)

\(\sqrt{\dfrac{4}{81}}.\dfrac{27}{8}-\sqrt{0,49}.\dfrac{1}{7}\)

\(=\dfrac{2}{9}.\dfrac{27}{8}-\dfrac{7}{10}.\dfrac{1}{7}\)

\(=\dfrac{3}{4}-\dfrac{7}{10}.\dfrac{1}{7}\)

\(=\dfrac{3}{4}-\dfrac{1}{10}\)

\(=\dfrac{30}{40}-\dfrac{4}{40}\)

\(=\dfrac{13}{20}\)

d)

\(\sqrt{\dfrac{16}{81}}.\dfrac{27}{8}-\sqrt{0,25}.\left(-2\right)^2\)

\(=\dfrac{4}{9}.\dfrac{27}{8}-\dfrac{1}{2}.4\)

\(=\dfrac{3}{2}-\dfrac{1}{2}.4\)

\(=\dfrac{3}{2}-2\)

\(=-\dfrac{1}{2}\)

\(#NguyễnNgọcKhánhLinh-VietNam\)

Sửa đề: \(3\sqrt{x+1}-1=38\)

=>3 căn x+1=39

=>căn x+1=13

=>x+1=169

=>x=168

\(\left(-\dfrac{1}{4}\right)^2.8+\sqrt{1\dfrac{9}{6}}:2\dfrac{1}{2}-\left|-\dfrac{3}{4}\right|\)

\(=\dfrac{1}{16}.8+\sqrt{\dfrac{15}{6}}:\dfrac{5}{2}+\dfrac{3}{4}\)

\(=\dfrac{8}{16}+1,3:2,5+\dfrac{3}{4}\)

\(=\dfrac{1}{2}+0,52+0,75\)

\(=0,5+0,52+0,75\)

\(=1.77\)

=>x-2^9 - √(2^4)=√66564x√16641

=>x-2^9 - √(2^4)=258x129

=>x-2^9 - √(2^4)=33411

=>x-512-4=33411

=>x-(512+4)=33411

=>x-516=33411

=>x=33411+516

=>x=33927

Vậy x=33927

\(=\dfrac{9}{4}-\left[\dfrac{1}{2}\times\dfrac{1}{2}-\dfrac{\sqrt{81}}{3}\right]\\ =\dfrac{9}{4}-\left(\dfrac{1}{4}-\dfrac{9}{3}\right)\\ =\dfrac{9}{4}-\left(\dfrac{1}{4}-3\right)\\ =\dfrac{9}{4}-\left(\dfrac{1-3\times4}{4}\right)\\ =\dfrac{9}{4}-\left(-\dfrac{11}{4}\right)\\ =\dfrac{9}{4}+\dfrac{11}{4}\\ =\dfrac{9+11}{4}\\ =\dfrac{20}{4}\\ =5\)

\(=\dfrac{9}{4}-[\dfrac{1}{4}-\dfrac{9.1}{3}]\)

\(=\dfrac{9}{4}-[\dfrac{1}{4}-\dfrac{9}{3}]\)

\(=\dfrac{9}{4}--\dfrac{11}{4}\)

\(=5\)

\(=\sqrt{\dfrac{9}{16}-3\cdot0.4+2}=\dfrac{\sqrt{545}}{20}\)

a: \(\Leftrightarrow\sqrt{x}\left(\sqrt{x}-3\right)=0\)

=>x=0 hoặc x=9

b; =>(x-1)(x-3)=0

=>x=3 hoặc x=1

1: =>x-1=4

=>x=5

2: =>2x+1=49

=>2x=48

=>x=24

3:=>x-1=0

=>x=1

\(=\dfrac{4}{5}\cdot5-\dfrac{7}{3}\cdot\sqrt{5}=4-\dfrac{7\sqrt{5}}{3}\)

=2/3-0,3+3/5

=10/15+9/15-3/10

=19/15-3/10

=38/30-9/30=29/30