Câu 1 

Ghép số lại ta được

9 + 8 + 5 + 6 - (9 + 8 + 5 + 6) = 0

Câu 2:

4 số 6 nhân lại được 6

4 số 1 nhân lại được 1

6 - 1 = 5

Câu 3:

Nhận thấy các cặp nhân đều xuất hiện các số lẻ và có chữ số 5 nên các cặp đó có tận cùng bằng 5

5 + 5 + 5 + 5 = 0

Chúc bạn học tốt !!!

\(d)\)\(43.78-43.48+30.80-30.23\)

\(=\)\(43.\left(78-48\right)+30.\left(80-23\right)\)

\(=\)\(43.30+30.57\)

\(=\)\(30.\left(43+57\right)\)

\(=\)\(30.100\)

\(=\)\(3000\)

\(43\times78-43\times48+30\times80-30\times23\)

\(=43\left(78-48\right)+30\times80-30\times23\)

\(=43\times30+30\times80-30\times23\)

\(=30\left(43+80-23\right)=30.100=3000\)

D)43.78-43.48+30.80-30.23

=43.(78-48)+30.(80-23)

=43.30+30.57

=30.(43+57)

=30.100

=3000

a,  2 17 + 17 2 9 15 - 3 15 2 4 - 4 2

=  2 17 + 17 2 9 15 - 3 15 16 - 16

=  2 17 + 17 2 9 15 - 3 15 . 0

= 0

b,  1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) ( 3 8 - 81 2 )

=  1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) ( 3 4 . 2 - 81 2 )

=  1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) ( 81 2 - 81 2 )

=  1 2 + 2 3 + 3 4 + 4 5 . ( 1 3 + 2 3 + 3 3 + 4 3 ) . 0

= 0

c,  7 24 + 7 23 : 7 22

=  7 24 : 7 22 + 7 23 : 7 22

=  7 24 - 22 + 7 23 - 22

=  7 2 + 7 1

= 49 + 7 = 56

a: Ta có: \(\left(2^{17}+17^2\right)\cdot\left(9^{15}-3^{15}\right)\cdot\left(2^4-4^2\right)\)

\(=\left(2^{17}+17^2\right)\cdot\left(9^{15}-3^{15}\right)\cdot\left(16-16\right)\)

=0

b: Ta có: \(\dfrac{8^{2017}-8^{2015}}{8^{2104}\cdot8}\)

\(=\dfrac{8^{2015}\cdot\left(8^2-1\right)}{8^{2105}}\)

\(=\dfrac{1\cdot63}{8^{90}}\)+

c: Ta có: \(\left(1^3+2^3+3^4+4^5\right)\cdot\left(1^3+2^3+3^3+4^3\right)\cdot\left(3^8-81^2\right)\)

\(=\left(1^3+2^3+3^4+4^5\right)\cdot\left(1^3+2^3+3^3+4^3\right)\cdot\left(3^8-3^8\right)\)

=0

d: Ta có: \(\left(2^8+8^3\right):\left(2^5\cdot2^3\right)\)

\(=\dfrac{2^8+2^9}{2^8}\)

=3

kết quả : 223

78+43+23+57+22

=(78+22)+(43+57)+23

=100+100+23

=200+23

=223

78+43+23+57+22={78+22}+{43+57}+23

                          =100+100+23

                          =223

\(\frac{\frac{6}{13}-\frac{6}{23}+\frac{6}{33}-\frac{6}{43}}{\frac{5}{13}-\frac{5}{23}+\frac{5}{33}-\frac{5}{43}}\)

= \(\frac{6.\left(\frac{1}{13}-\frac{1}{23}+\frac{1}{33}-\frac{1}{43}\right)}{5.\left(\frac{1}{13}-\frac{1}{23}+\frac{1}{33}-\frac{1}{43}\right)}\)

= \(\frac{6}{5}\)

k cho mình nhé

\(A=\frac{7}{3\times13}+\frac{7}{13\times23}+...+\frac{7}{53\times63}\)

\(A=\frac{7}{10}.\left[\left(\frac{1}{3}-\frac{1}{13}\right)+\left(\frac{1}{13}-\frac{1}{23}\right)+....+\left(\frac{1}{53}-\frac{1}{63}\right)\right]\)

\(A=\frac{7}{10}.\left(\frac{1}{3}-\frac{1}{13}+\frac{1}{13}-\frac{1}{23}+....+\frac{1}{53}-\frac{1}{63}\right)\)

\(A=\frac{7}{10}.\left(\frac{1}{3}-\frac{1}{63}\right)\)

\(A=\frac{7}{10}.\frac{20}{63}\)

\(A=\frac{2}{9}\)

huỳnh thị ngân hà, nau te, trần như tính sao ra z? 

S = 13+10+23+20+33+30+...+103+100

S =  13+23+33+...+103+10.100

S = 3025+1000

S = 4025

6020 , chắc chắn đúng 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000%