=>tuấn có số bi là :

45x2=90 viên

=>tổng số bi của tuấn và hùng là :

90 :1/6=540 viên

=>cả ba bạn có số bi là :

540+45=585 viên

cạnh-góc-cạch là vầy nè:

vẽ tia phân giác góc A là AT

ta có

A1+B+T1=180⁰

A2+C+T2=180⁰

mà A1=A2,B=C=>T1=T2

xét t/gTAB và t/gTAC

chung AT

A1=A2

T1=T2

=>t/g ABT= t/g ACT(cgc)

=>AB=AC

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

\(\left(x^4\right)^2=x^{12}:x^5\\ x^8=x^{12-5}\\ x^8=x^7\\ \Rightarrow x=1\)

\(\dfrac{x}{-15}=\dfrac{-60}{x}\\ x.x=-60.\left(-15\right)\\ x^2=900\\ x^2=30^2=\left(-30\right)^2\\ \Rightarrow x=\pm30\)

1)

\(\dfrac{5}{7}+\dfrac{2}{3}.x=\dfrac{3}{10}\\ \dfrac{2}{3}.x=\dfrac{3}{10}-\dfrac{5}{7}\\ \dfrac{2}{3}.x=\dfrac{21-50}{70}\\ =\dfrac{2}{3}.x=-\dfrac{29}{70}\\ x=-\dfrac{29}{70}.\dfrac{3}{2}\\ x=-\dfrac{87}{140}\)

2)

\(\left(x-\dfrac{1}{2}\right):\dfrac{1}{3}+\dfrac{5}{7}=9\dfrac{5}{7}\\ \left(x-\dfrac{1}{2}\right):\dfrac{1}{3}=\dfrac{68}{7}-\dfrac{5}{7}\\ \left(x-\dfrac{1}{2}\right):\dfrac{1}{3}=9\\ x-\dfrac{1}{2}=9.\dfrac{1}{3}\\ x-\dfrac{1}{2}=3\\ x=3+\dfrac{1}{2}\\ x=\dfrac{18+3}{6}\\ x=\dfrac{21}{6}\\ x=\dfrac{7}{2}\)

a)

\(3:\left(\dfrac{9}{4}\right)=\dfrac{3}{4}:\left(6.x\right)\\ \Rightarrow3.6.x=\dfrac{3}{4}.\dfrac{9}{4}\\ x=\dfrac{3}{4}.\dfrac{9}{4}.\dfrac{1}{3}.\dfrac{1}{6}\\ x=\dfrac{3}{4.4.2}\\ x=\dfrac{3}{32}\)

b)

\(4,5:0,3=\left(5.0,09\right):\left(0,01.x\right)\\ 0,01.x.4,5=5.0,09.0,3\\ x=5.\dfrac{9}{100}.\dfrac{3}{10}.100.\dfrac{10}{45}\\ x=3\)

d)

\(\left(\dfrac{1}{9}.x\right)=\dfrac{7}{4}:\dfrac{2}{25}\\ \left(\dfrac{1}{9}.x\right)=\dfrac{7}{4}.\dfrac{25}{2}\\ x:\dfrac{7}{4}=\dfrac{25}{2}:\dfrac{1}{9}\\ x=\dfrac{25}{2}.9.\dfrac{7}{4}\\ x=\dfrac{1575}{8}\\ x=196\dfrac{7}{8}\)

e)

\(\dfrac{-2}{x}=\dfrac{-x}{\dfrac{8}{25}}\\ -x.x=-2.\dfrac{8}{25}\\ -x^2=-\dfrac{16}{25}=-\dfrac{4^2}{5^2}\\ -x^2=-\left(\dfrac{4}{5}\right)^2\\ \Rightarrow x=\dfrac{4}{5}\)

Chúc bạn học tốt

1)

\(2^x=4^5.4^3\\ 2^x=\left(2^2\right)^5.\left(2^2\right)^3\\ 2^x=2^{10}.2^6\\ 2^x=2^{10+6}\\ 2^x=2^{16}\\ \Rightarrow x=\pm16\)

2)

\(2^x=32^5.64^6\\ 2^x=\left(2^5\right)^5.\left(2^6\right)^6\\ 2^x=2^{25}.2^{36}\\ 2^x=2^{61}\\ \Rightarrow x=61\)

3)

\(2^x=4^3.8^4.16^5\\ 2^x=\left(2^2\right)^3.\left(2^3\right)^4.\left(2^4\right)^5\\ 2^x=2^6.2^{12}.2^{20}\\ 2^x=2^{6+12+20}\\ 2^x=2^{38}\\ \Rightarrow x=\pm38\)

Chúc bạn học tốt

2)

\(2^x=8^3.8^{-10}.8^3\\ 2^x=\left(2^3\right)^3.\left(2^3\right)^{-10}.\left(2^3\right)^3\\ 2^x=2^9.2^{-30}.2^9\\ 2^x=2^{9-30+9}=2^{-12}\\ \Rightarrow x=-12\)

3)

\(2^x=\dfrac{4^7}{4^3}\\ 2^x=\dfrac{\left(2^2\right)^7}{\left(2^2\right)^3}\\ 2^x=\dfrac{2^{14}}{2^6}\\ 2^x=2^{14-6}\\ 2^x=2^8\\ \Rightarrow x=\pm8\)

Chúc bạn học tốt

Ta có: \(\widehat{xAB}=\widehat{yBA}=120^o\)

mà \(\widehat{xAB}\) và \(\widehat{yBA}\) đều nằm ở vị trí so le trong

\(\Rightarrow Ax\)//\(By\)