=1 nhưng mình ko biết trình bày bạn nào làm biết trình bày thì viết hô mình nha ?

Lời giải:
a. $=5.9+112-31=45+112-31=157-31=126$

b. $=-31-82-17=-(31+82+17)=-130$

c. $=6.(-8)+20+12=-48+32=-(48-32)=-16$

d. Trùng với câu b.

a)(nhân N vs 3^2 rồi trừ đi N) chia cho 3^2-1

b)(nhân P vs 5^3 rồi trừ đi P) chia cho 5^3-1

a, \(N=1+3^2+...+3^{100}\)

\(\Rightarrow3^2N=3^2+3^4+...+3^{102}\)

\(\Rightarrow3^2N-N=\left(3^2+3^4+...+3^{102}\right)-\left(1+3^2+...+3^{100}\right)\)

\(\Rightarrow8N=3^{102}-1\)

\(\Rightarrow N=\frac{3^{102}-1}{8}\)

\(P=1+5^3+5^6+...+5^{99}\)

\(5^3P=5^3+5^6+5^9+...+5^{102}\)

\(5^3P-P=\left(5^3+5^6+5^9+...+5^{102}\right)-\left(1+5^3+5^6+...+5^{99}\right)\)

\(124P=5^{102}-1\)

\(P=\frac{5^{102}-1}{124}\)

5: \(=3-\dfrac{1}{4}+\dfrac{2}{3}-5+\dfrac{1}{3}+\dfrac{6}{5}-6+\dfrac{7}{4}-\dfrac{3}{2}\)

\(=3-5-6+\dfrac{-1}{4}+\dfrac{7}{4}+\dfrac{2}{3}+\dfrac{1}{3}+\dfrac{6}{5}-\dfrac{3}{2}\)

\(=-8+\dfrac{3}{2}+1+\dfrac{-3}{10}\)

\(=-7+\dfrac{15-3}{10}=-7+\dfrac{6}{5}=-\dfrac{29}{5}\)

6: \(=6-\dfrac{2}{3}+\dfrac{1}{2}-5-\dfrac{5}{3}+\dfrac{3}{2}-3+\dfrac{7}{3}-\dfrac{5}{2}\)

\(=6-5-3-\dfrac{2}{3}-\dfrac{5}{3}+\dfrac{7}{3}+\dfrac{1}{2}+\dfrac{3}{2}-\dfrac{5}{2}\)

\(=-2-\dfrac{1}{2}=-\dfrac{5}{2}\)

7: \(=\dfrac{5}{3}-\dfrac{3}{7}+9-2-\dfrac{5}{7}+\dfrac{2}{3}+\dfrac{8}{7}-\dfrac{4}{3}-10\)

\(=9-2-10+\dfrac{5}{3}+\dfrac{2}{3}-\dfrac{4}{3}+\dfrac{-3}{7}-\dfrac{5}{7}+\dfrac{8}{7}\)

=-3+1

=-2

8: \(=8-\dfrac{9}{4}+\dfrac{2}{7}+6+\dfrac{3}{7}-\dfrac{5}{4}-3-\dfrac{2}{4}+\dfrac{9}{7}\)

\(=8+6-3+\dfrac{2}{7}+\dfrac{3}{7}+\dfrac{9}{7}-1-\dfrac{2}{4}\)

\(=11+2-1-\dfrac{1}{2}\)

=11+1/2

=11,5

Lời giải chi tiết:

2=1+1          6=2+4          8=5+3          10=8+2

3=1+2          6=3+3          8=4+4          10=7+3

4=3+1          7=6+1          9=8+1          10=6+4

4=2+2          7=5+2          9=7=2          10=5+5

5=4+1          7=4+3         9=6+3           10=10+0

5=3+2          8=7+1         9=5=4           10=0+10

6=5+1          8=6=2         10=9+1         1=0+1

cop hết mạng kìa

xàm??

.-. ?

spam à

= (1+1+1+1)+(2+2+2)+(3+3+3+3)+(4+4+4+4)+(5+5+5+5)+(6+6+6+6)+(7+7+7+7)+(8+8+8+8)+(9+9+9+9)+10
4 + 6 + 12 + 16 + 20 + 24 + 28 + 32 + 36 + 10 =
= 188

\(\dfrac{\left(\dfrac{2}{3}\right)^3\cdot\left(-\dfrac{3}{4}\right)^2\cdot\left(-1\right)^5}{\left(\dfrac{2}{5}\right)^2\cdot\left(-\dfrac{5}{12}\right)^3}\)\(=\dfrac{\dfrac{2^3\cdot\left(-3\right)^2\cdot\left(-1\right)}{3^3\cdot4^2}}{\dfrac{2^2\cdot\left(-5\right)^3}{5^2\cdot12^3}}\)

\(=\dfrac{\dfrac{2^3\cdot3^2\cdot\left(-1\right)}{3^3\cdot\left(2^2\right)^2}}{\dfrac{2^2\cdot\left(-5\right)^3}{5^2\cdot\left(2^2\cdot3\right)^3}}=\dfrac{\dfrac{2^3\cdot3^2\cdot\left(-1\right)}{3^3\cdot2^4}}{\dfrac{2^2\cdot5^2\cdot\left(-5\right)}{5^2\cdot2^6\cdot3^3}}=\dfrac{\dfrac{-1}{3\cdot2}}{\dfrac{-5}{2^4\cdot3^3}}\)

\(=\dfrac{-\dfrac{1}{6}}{27\cdot16}=-\dfrac{1}{6}:432=-\dfrac{1}{6}\cdot\dfrac{1}{432}=-\dfrac{1}{2592}\)

14dm5cm=14,5dm;3dm7cm=3,7dm

chu vi hình chữ nhật đó là:

(14,5+3,7)x2=36,4(dm)

ĐS:36,4dm

14 dm 5 cm = 14,5 dm 

3 dm 7 cm = 3,7 dm 

Chiều rộng HCN là :

14,5 - 3,7 = 10,8 ( dm )

chu vi HCN là :

( 14,5 + 10,8 ) x 2 = 50,6 ( dm )

ĐS:..

ban lam sai roi