\(=-375\left(69+31\right)=-375\cdot100=-37500\)

La 2772 noa ban

      chuc ban hoc gioi noa

cho minh di

đng kết quả là như vạy nhưng cho mk hoi bn lm thế nào

bài này có 2 cách nha bn 

cách làm là j vậy làm ơn nói mk biết ik bn ơi

Lời giải:

$A=(99-97)+(95-93)+(91-89)+...+(7-5)+(8-1)$

$=\underbrace{2+2+2+...+2}_{24}+7$

$=2\times 24+7$

$=55$

\(A=\left(6-\dfrac{2}{3}+\dfrac{1}{2}\right)-\left(5+\dfrac{5}{3}-\dfrac{3}{2}\right)-\left(3-\dfrac{7}{3}+\dfrac{5}{2}\right)\\ A=\dfrac{35}{6}-\dfrac{31}{6}-\dfrac{19}{6}=-\dfrac{15}{6}\)

a) \(29.31=\left(30-1\right)\left(30+1\right)=30^2-1=900-1=899\)

b) \(33,3^2-2.33,3.3,3+3,3^2=\left(33,3-3,3\right)^2=30^2=900\)

c) \(20,1.19,9=\left(20+0,1\right)\left(20-0,1\right)=20^2-0,1^2=400-0.01=399,99\)

d) \(37^2+2.37.13+13^2=\left(37+13\right)^2=50^2=2500\)

a, \(29.31=\left(30-1\right)\left(30+1\right)=30^2-1=899\)

b, \(33,3^2-2.33,3.3,3+3,3^2=\left(33,3-3,3\right)^2=30^2=900\)

c, \(20,1.19,9=\left(20-0,1\right)\left(20+0,1\right)=20^2-0,1^2=399,99\)

d, \(37^2+2.37.13+13^2=\left(37+13\right)^2=50^2=2500\)

a: \(29\cdot31=30^2-1=900-1=899\)

b: \(33.3^2-2\cdot33.3\cdot3.3+3.3^2\)

\(=\left(33.3-3.3\right)^2\)

=900

c: \(20.1\cdot19.9=20^2-0.1^2=399.9\)

d: \(37^2+2\cdot37\cdot13+13^2=\left(37+13\right)^2=2500\)

\(=\left(300-52\right)\left(300+52\right)=300^2-52^2\\ =90000-2704=87296\)

1

a)48,124

b)-28,538

c)56,96

d)111,5

Câu 2

a)132,1

b)21,35

Câu 3

a)4,8

b)71,5

a)
\(=\dfrac{4.4.25+4.11.4.25}{29.2.48+71.2.48}=\dfrac{400+400.11}{96.29+71.96}=\dfrac{400\left(1+11\right)}{96\left(29+71\right)}=\dfrac{400.12}{96.100}=\dfrac{2.2.100.12}{12.2.2.2.100}=\dfrac{1}{2}\)

a: \(1968\cdot15+1968\cdot84+1968\)

\(=1968\left(15+84+1\right)\)

\(=1968\cdot100=196800\)

b: \(6412+5378+3582+4628\)

\(=\left(6412+4628\right)+\left(5378+3582\right)\)

\(=11040+8960=20000\)

c: \(178\cdot101-178\)

\(=178\cdot101-178\cdot1\)

\(=178\left(101-1\right)=178\cdot100=17800\)

d: \(153\cdot8+153+153\)

\(=153\left(8+1+1\right)\)

\(=153\cdot10=1530\)