\(\sqrt{x^2-x+19}+\sqrt{7x^2+8x+13}+\sqrt{13x^2+17x+17}+3x\sqrt{3}\)

Tách thành các bình phương dưới căn sau đó tìm chặn đc nhé 

Bạn nào làm đc thì 3 tick

Lớp nguồn ra nhiều bài khó nhỉ

\(\dfrac{3}{7}.\dfrac{11}{13}-\dfrac{3}{13}.\dfrac{15}{7}.\dfrac{-17}{7}\)

= \(\dfrac{33}{91}-\dfrac{-765}{673}\)

= 1,4993387

Trả lời

Bài 1:

a)(45-25).(-11)+29.(-3-17)

=20.(-11)+29.(-20)

=20.(-11)+(-29).20

=20.[(-11)+(-29)]

=20.(-30)

=-600

b)(36-6).(-5)+21.(-17-3)

=30.(-5)+21.(-20)

=(-150)+(-420)

=-570

trả lời:

a,(45-25).(-11)+29.(-3-17)

  =20.(-11)+29.(-20)

  =20.(-11)+(-29).20

  =20.[(-11)+(-29).20

  =20.(-30)

  =-600

học tốt

16. 7 x − 16. 5 2 x  = 0

⇔  7 x  =  5 2 x  ⇔  7 / 25 x  =  7 / 25 0  ⇔ x = 0

1. <=>15 (2x+4)= 7(4x-2)

<=>30x+60= 28x-14

<=>2x= -74

<=>x= -37

2. <=> -5(12-7x)= -13(4-3x)

<=> -60+35x = -52+39x

<=> -4x= 8

<=> x= -2

3.<=> 88x-16 = 77x+55

<=> 11x= 71

<=> x=71/11

\(7\frac{x}{2.5}+7\frac{x}{5.8}+.....+7.\frac{x}{17.20}=\frac{21}{10}\)

\(7\left(\frac{x}{2.5}+\frac{x}{5.8}+...+\frac{x}{17.20}\right)=\frac{21}{10}\)

\(\frac{x}{2.5}+\frac{x}{5.8}+...+\frac{x}{17.20}=\frac{21}{70}\)

\(\frac{x.3}{2.5.3}+\frac{x.3}{5.8.3}+...+\frac{x.3}{17.20.3}=\frac{21}{70}\)

\(x.\frac{1}{3}.\left(\frac{3}{2.5}+\frac{3}{5.8}+...+\frac{3}{17.20}\right)=\frac{21}{70}\)

\(x.\frac{1}{3}.\left(\frac{1}{2}-\frac{1}{20}\right)=\frac{21}{70}\)

\(x.\frac{1}{3}.\frac{9}{20}=\frac{21}{70}\)

=> \(x=2\)

\(x=\frac{7x}{2}\)\(-\frac{7x}{5}+\)\(\frac{7x}{5}\)\(-\frac{7x}{8}\)\(+\frac{7x}{8}\)\(-\frac{7x}{11}\)\(+\frac{7x}{11}\)\(-\frac{7x}{14}\)\(+\frac{7x}{14}\)\(-\frac{7x}{17}+\)\(\frac{7x}{17}\)\(-\frac{7x}{20}\)\(=\frac{21}{10}\)

\(x=\frac{7x}{2}\)\(-\frac{7x}{20}\)\(=\frac{21}{10}\)

\(x=\frac{7x.10}{20}\)\(+\frac{7x}{20}\)\(=\frac{21}{10}\)

\(x=\frac{7x.10+7x}{20}\)\(=\frac{21}{10}\)

\(x=\frac{7x.\left(10+2\right)}{20.2}\)\(=\frac{7x.12}{40}\)\(=\frac{21}{10}\)

\(=>\frac{7x.12:4}{40:4}=\)\(\frac{21}{10}\)

\(=>x=1\)