d) \(\dfrac{\sqrt{5x-4}}{\sqrt{x+2}}=2\left(đk:x\ge\dfrac{4}{5}\right)\)

\(\Leftrightarrow\sqrt{5x-4}=2\sqrt{x+2}\)

\(\Leftrightarrow5x-4=4x+8\)

\(\Leftrightarrow x=12\left(tm\right)\)

c)

\(-\dfrac{3}{5}.\dfrac{2}{7}+-\dfrac{3}{5}.\dfrac{5}{7}-\dfrac{-13}{5}\\ =-\dfrac{3}{5}\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\dfrac{13}{5}\\ =-\dfrac{3}{5}.1+\dfrac{13}{5}\\ =-\dfrac{3}{5}+\dfrac{13}{5}\\ =\dfrac{13-3}{5}\\ =\dfrac{10}{5}\\ =2\)

d)

\(\dfrac{8}{15}.\dfrac{-13}{27}+\dfrac{8}{15}.\dfrac{-14}{27}+1\dfrac{2}{3}\\ =\dfrac{8}{15}\left(-\dfrac{13}{27}-\dfrac{14}{27}\right)+\dfrac{5}{3}\\ =\dfrac{8}{15}.-1+\dfrac{5}{3}\\ =-\dfrac{8}{15}+\dfrac{5.5}{15}\\ =\dfrac{25-8}{15}\\ =\dfrac{17}{15}\)

C.

=-3/5 . (2/7+5/7) + 13/5

=-3/5 (7/7) + 13/5

-3/5 + 13/5

=10/5

=2

d.

=8/15(-13/27 - 14/27) + 5/3

=8/15 . (-27/27) + 5/3

=-8/15 + 5/3

=-8/15 + 25/15

=17/15

a: =x^3+3x^2+3x+1-x(x^2-4x+4)-1

=x^3+3x^2+3x-x^3+4x^2-4x

=7x^2-x

b: =x^3-6x^2+12x-8-x^3+6x^2

=12x-8

d: =x^3-8-x^3+4=-4

c: Sửa đề: (5x-1)^2+2(1-5x)(4+5x)+(5x+4)^2

=(1-5x)^2+2(1-5x)(4+5x)+(4+5x)^2

=(1-5x+4+5x)^2=5^2=25

a)2x²-7x-2x²-2x=7

-9x=7

x=-7/9

b)3x²+24x-x²-2x²-2x=2

22x=2

x=1/11

c: \(3x\left(x-7\right)-2\left(x-7\right)=0\)

\(\Leftrightarrow\left(x-7\right)\left(3x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=7\\x=\dfrac{2}{3}\end{matrix}\right.\)

d: \(7x^2-28=0\)

\(\Leftrightarrow\left(x-2\right)\left(x+2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\)

Bạn ơi chỉ mình câu c với đc kh ạ. Mình mới tìm ra góc ACD = góc AHE à, còn cái nào nữa để chứng mình đồng dạng v ạ

d: =64+216+343+2=625=25^2

Giúp em với ạ ☺️

c) 1,128

d) 35,217

c)0,24 x 4,7 =1,128

d)7,826 x 4,5 = 35,217