\(a,5^x+5^{x+2}=650\\ \Rightarrow5^x+5^x.5^2=650\\ \Rightarrow5^x\left(1+5^2\right)=650\\ \Rightarrow5^x.26=650\\ \Rightarrow5^x=25\\ \Rightarrow5^x=5^2\\ \Rightarrow x=2\)

\(b,\left(4x+1\right)^2=25.9\\\Rightarrow\left(4x+1\right)^2=225\\ \Rightarrow\left[{}\begin{matrix}4x+1=15\\4x+1=-15\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{7}{2}\\x=-4\end{matrix}\right.\)

\(c,2^x+2^{x+3}=144\\ \Rightarrow2^x+2^x.2^3=144\\ \Rightarrow2^x\left(1+2^3\right)=144\\ \Rightarrow2^x=144:\left(1+2^3\right)\\ \Rightarrow2^x=16\\ \Rightarrow2^x=2^4\\ \Rightarrow x=4\)

\(d,3^{x+2}=9^{x+3}\\ \Rightarrow3^{x+2}=\left(3^2\right)^{x+3}\\ \Rightarrow3^{x+2}=3^{2x+6}\\ \Rightarrow x+2=2x+6\\ \Rightarrow x-2x=6-2\\ \Rightarrow-x=4\\ \Rightarrow x=-4\)

\(e,x^{15}=x^2\\ \Rightarrow x^{15}-x^2=0\\ \Rightarrow x^2\left(x^{13}-1\right)=0\\ \Rightarrow\left[{}\begin{matrix}x^2=0\\x^{13}-1=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)

\(\sqrt{4}-\sqrt{7}+\sqrt{4}+\sqrt{7}\\ =\left(\sqrt{4}+\sqrt{4}\right)+\left(-\sqrt{7}+\sqrt{7}\right)\\ =2+2+0\\ =4\)

1,

Hình 1

Do a// b

\(\Rightarrow\widehat{ACD}=x=135^o\) (hai góc đồng vị )

Hình 2

Do a// b

\(\Rightarrow x=\widehat{EFN}=90^o\) (hai góc so le trong )

Bài 2

a, Đường thẳng \(b//a\) vì có hai góc \(=45^o\) ở vị trí so le trong

b, \(d//c\) Do hai góc bằng \(60^o\) ở vị trí so le trong

c, \(m//n\) Do có hai góc bằng \(60^o\) ở vị trí đồng vị

@seven 

\(b,\dfrac{x^2+x}{2x+2}=\dfrac{A}{2}\\ \Rightarrow2\left(x^2+x\right)=A.\left(2x+2\right)\\ \Rightarrow A=\dfrac{2\left(x^2+x\right)}{2x+2}=\dfrac{2x\left(x+1\right)}{2\left(x+1\right)}=x\)

Vậy \(A=x\)

\(c,\dfrac{2x-1}{\left(x-3\right).A}=\dfrac{1}{x^2-4x+3}\\ \Leftrightarrow\dfrac{2x-1}{\left(x-3\right).A}=\dfrac{1}{\left(x-1\right)\left(x-3\right)}\\ \Rightarrow\left(x-3\right).A=\left(2x-1\right)\left(x-1\right)\left(x-3\right)\\ \Leftrightarrow A=\left(2x-1\right)\left(x-1\right)\\=2x^2-x-2x+1\\ =2x^2-3x+1\)

Vậy \(A=2x^2-3x+1\)

_@seven

\(1,\left[\left(-\dfrac{2}{5}\right)+\dfrac{1}{3}\right]-\left(\dfrac{3}{5}-\dfrac{1}{3}\right)=-\dfrac{2}{5}+\dfrac{1}{3}-\dfrac{3}{5}+\dfrac{1}{3}\\ =\left(-\dfrac{2}{5}-\dfrac{3}{5}\right)+\left(\dfrac{1}{3}+\dfrac{1}{3}\right)\\ =\dfrac{-2-3}{5}+\dfrac{1+1}{3}\\ =-\dfrac{5}{5}+\dfrac{2}{3}\\ =-1+\dfrac{2}{3}\\ =\dfrac{-3+2}{3}=-\dfrac{1}{3}\\ b,\left(\dfrac{3}{2}-\dfrac{3}{4}\right)-\left(0,25+\dfrac{1}{2}\right)\\ =\left(\dfrac{3}{2}-\dfrac{3}{4}\right)-\left(\dfrac{1}{4}+\dfrac{1}{2}\right)\\ =\dfrac{3}{2}-\dfrac{3}{4}-\dfrac{1}{4}-\dfrac{1}{2}\\ =\left(\dfrac{3}{2}-\dfrac{1}{2}\right)+\left(-\dfrac{3}{4}-\dfrac{1}{4}\right)\\ =\dfrac{3-1}{2}+\dfrac{-3-1}{4}\\ =\dfrac{2}{2}-\dfrac{4}{4}=1-1=0\)

Phong said that he needed to learn more vocabulary

His brother told him that he could use his computer that day 

Mai said to Nam that she could not go to the movies with him

Phong asked Peter if he enjoyed reading 

Hoa asked Lan if she liked sports 

She asked Nam if his sister and brother went to the same school

She asked her mom if there were some oranges in the fridge 

He asked his friend if it (the weather ) would rain the next morning 

Bài 37

\(a,36=6^2\\ 64=8^2\\ 169=13^2\\ 225=15^2\\ 361=19^2\\ 10000=100^2\)

b,

 \(8=2^3\\ 27=3^3\\125=5^3\\ 216=6^3\\ 343=7^3\\ 8000=20^3 \)

Bài 38 bạn chụp lại đề đc ko 

chương trình mới :v?