1+2+3+4x10

=1+2+3+40

=3+3+40

=6+40

=46

k mình nha

Chúc bạn học giỏi

kết quả là 5x10

tra loi 5x10

Đặt \(A=\dfrac{2}{1.5}+\dfrac{3}{5.11}+\dfrac{4}{11.19}+\dfrac{5}{19.29}+\dfrac{6}{29.41}\)

\(2A=\dfrac{4}{1.5}+\dfrac{6}{5.11}+\dfrac{8}{11.19}+\dfrac{10}{19.29}+\dfrac{12}{29.41}\)

\(2A=\dfrac{1}{1}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{19}+\dfrac{1}{19}-\dfrac{1}{29}+\dfrac{1}{29}-\dfrac{1}{41}\)

\(2A=\dfrac{1}{1}-\dfrac{1}{41}=\dfrac{40}{41}\)

\(A=\dfrac{40}{41}:2=\dfrac{20}{41}\)

Đặt \(B=\dfrac{1}{1.4}+\dfrac{2}{4.10}+\dfrac{3}{10.19}+\dfrac{4}{19.31}\)

Tương tự ta dễ dàng tình đc:

\(B=\dfrac{10}{31}=\dfrac{20}{62}\)

Ta có: \(\dfrac{20}{41}< \dfrac{20}{62}\Rightarrow A< B\)

Vậy ........................

Chúc bn học tốt

Đặt A=2/1.5+3/5.11+...+6/29.41

B=1/1.4+2/4.10+3/10.19+4/19.31

2A=4/1.5+6/5.11/+...+12/29.41

2A=1-1/5+1/5-1/11+...+1/29-1/41

2A=1-1/41

2A=40/41

A=20/41

3B=3/1.4+6/4.10+9/10.19+12/19.31

3B=1-1/4+1/4-1/10+1/10-1/19+1/19-1/31

3B=1-1/31

3B=30/31

B=10/31

Vì 10/31<20/41 nên B<A

Giải:

Đặt \(A=\dfrac{2}{1.5}+\dfrac{3}{5.11}+\dfrac{4}{11.19}+\dfrac{5}{19.29}+\dfrac{6}{29.41}\) 

\(A=\left(\dfrac{4}{1.5}+\dfrac{6}{5.11}+\dfrac{8}{11.19}+\dfrac{10}{19.29}+\dfrac{12}{29.41}\right):2\) 

\(A=\left(\dfrac{1}{1}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{19}+\dfrac{1}{19}-\dfrac{1}{29}+\dfrac{1}{29}-\dfrac{1}{41}\right):2\) 

\(A=\left(\dfrac{1}{1}-\dfrac{1}{41}\right):2\) 

\(A=\dfrac{40}{41}:2\) 

\(A=\dfrac{20}{41}\) 

Đặt \(B=\dfrac{1}{1.4}+\dfrac{2}{4.10}+\dfrac{3}{10.19}+\dfrac{4}{19.31}\) 

\(B=\left(\dfrac{3}{1.4}+\dfrac{6}{4.10}+\dfrac{9}{10.19}+\dfrac{12}{19.31}\right):3\) 

\(B=\left(\dfrac{1}{1}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{19}+\dfrac{1}{19}-\dfrac{1}{31}\right):3\) 

\(B=\left(\dfrac{1}{1}-\dfrac{1}{31}\right):3\) 

\(B=\dfrac{30}{31}:3\) 

\(B=\dfrac{10}{31}\) 

Vì \(\dfrac{20}{41}>\dfrac{10}{31}\) nên A>B

Lời giải:

\(\frac{2}{5}\times \frac{10}{7}\times \frac{-3}{4}\times \frac{10}{7}+\frac{5}{2}:2=\frac{-30}{49}+\frac{5}{4}=\frac{125}{196}\)

Em nên gõ công thức trực quan để đề bài được rõ ràng nhé

x²-9-(-2)²=4x10+2³

x²-9-4=40+8

x²     =40+8+4+9=61

x=\(\sqrt{61}\)

= 40353607 x 0

= 0

bằng 0 đó k cho mình nha

nólaf0

\(2\times3=6\)

\(8-4=4\)

\(4\times10=40\)

\(5\times1=5\)

\(2\times9=18\)

\(5\times2=10\)

2x3=6        8-4=4        4x10=40

5x1=5         2x9=18      5x2=10

2×3=6

8-4=4

5×1=5

2×9=18

5×2=10