ĐKXĐ: \(x\notin\left\{10;-10\right\}\)

Ta có: \(\dfrac{720}{x+10}+4=\dfrac{720}{x-10}\)

\(\Leftrightarrow\dfrac{720\left(x-10\right)}{\left(x+10\right)\left(x-10\right)}+\dfrac{4\left(x^2-100\right)}{\left(x+10\right)\left(x-10\right)}=\dfrac{720\left(x+10\right)}{\left(x+10\right)\left(x-10\right)}\)

Suy ra: \(720x-7200+4x^2-400-720x-7200=0\)

\(\Leftrightarrow4x^2=14800\)

\(\Leftrightarrow x^2=3700\)

hay \(x\in\left\{10\sqrt{37};-10\sqrt{37}\right\}\)

ĐKXĐ: \(x\ne\pm10\)

\(\Leftrightarrow\dfrac{180}{x-10}-\dfrac{180}{x+10}=1\)

\(\Leftrightarrow\dfrac{180\left(x+10-x+10\right)}{\left(x-10\right)\left(x+10\right)}=1\)

\(\Leftrightarrow\dfrac{3600}{x^2-100}=1\)

\(\Rightarrow x^2-100=3600\)

\(\Leftrightarrow x^2=3700\)

\(\Leftrightarrow x=\pm10\sqrt{37}\) (thỏa mãn)

. là chia à

\(720\left(20-71\right)-71\left(-720\right)\)

\(=720.20-720.71+71.720\)

\(=720.20\)

\(=14400\)

bằng 14400 nhé bạn 

thanks

a) Ta có:

192 = 2⁶.3

102 = 2.3.17

UCLN(192,102) = 2.3 = 6

b) Ta có:

216 = 2³.3³

720 = 2⁴.3².5

UCLN(216,720) = 2³.3² = 8.9 = 72

c) Ta có:

480 = 2⁵.3.5

720 = 2⁴.3².5

48 = 2⁴.3

UCLN(480,720,48) = 2⁵.3 = 32.3 = 96

a: UCLN(192;102)=6

b: UCLN(216;720)=72

c: UCLN(480;720;48)=48

\(=7^{20}:7^{15}\left(15+34\right)=7^5\cdot49=7^7\)

Kết quả: 1 10