a, <=>(-5)^x=(-5)³

<=> x=3

b, <=> 5^2x=5²²

<=> x=11

c, 3^2x=3¹⁷.3¹⁵

<=> 3^2x=3³²

<=> x=16

d,2^x+1=2²⁵

<=> x+1=25

<=> x=24

Chúc hok tốt!!!

a)x=3

b)x=11

c)x=16

d)x=24

dễ thì tự giải đi

a)x=11

b) x=1

c) x=2

d) x=15

e) x=3

g) x=15

1 ) x = 0,375

2) x= 7,530514717

nhoc oi tra loi han hoi ra

\(S=\frac{3}{\left(1.2\right)^2}+\frac{5}{\left(2.3\right)^2}+...+\frac{61}{\left(30.31\right)^2}\)

\(S=\frac{3}{1^2.2^2}+\frac{5}{2^2.3^2}+...+\frac{61}{30^2.31^2}\)

\(S=\frac{3}{1.4}+\frac{5}{4.9}+...+\frac{61}{900.961}\)

\(S=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{9}+...+\frac{1}{900}-\frac{1}{961}\)

\(S=1-\frac{1}{961}\)

\(S=\frac{960}{961}\)

Với \(n\ge1\)thì \(\frac{2n+1}{n^2\left(n+1\right)^2}=\frac{n^2+2n+1-n^2}{n^2\left(n+1\right)^2}=\frac{\left(n+1\right)^2-n^2}{n^2\left(n+1\right)^2}=\frac{\left(n+1\right)^2}{n^2\left(n+1\right)^2}-\frac{n^2}{n^2\left(n+1\right)^2}\)

Do đó \(S=\frac{3}{\left(1\cdot2\right)^2}+\frac{5}{\left(2\cdot3\right)^2}+...+\frac{4017}{\left(2008\cdot2009\right)^2}=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{9}+...+\frac{1}{2008^2}-\frac{1}{2009^2}\)

\(=1-\frac{1}{2009^2}\)

sao bạn hôm đăng bài lớp 8 hôm thì đăng bài lớp 6 vậy

\(\frac{5.\left(2^2.3^2\right)^9.\left(2^2\right)^6-2.\left(2^2.3\right)^{14}.3^4}{5.2^{28}.3^{18}+7.2^{29}.3^{18}}\)

\(=\frac{5.2^{18}.3^{18}.2^{12}-2.2^{28}.3^{14}.3^4}{2^{28}.3^{18}.\left(5+7.2\right)}\)

\(=\frac{5.2^{30}.3^{18}-2^{29}.3^{18}}{2^{28}.3^{18}.19}=\frac{2^{28}.3^{18}.\left(5.4-2\right)}{2^{28}.3^{18}.19}\)

\(=\frac{5.4-2}{19}=\frac{18}{19}\)