=180+144-216+144

=144+(216-180)

=144+36

=180

Đ/S : 180

=180 nha ban 

   36 x 5 + 72 x 2 - 216 + 144

= 36 x 5 + 36 x 2 x 2 - 36 x 6 + 36 x 4

= 36 x ( 5 + 2 + 2 - 6 + 4 )

= 36 x       5

=    180

36 x 5 + 72 x 2 - 216 + 144

= 252

\(36\text{×}5+72\text{×}2-216+144\)

\(=36\text{×}5+36\text{×}2\text{×}2-36\text{×}6+36\text{×}4\)

\(=36\text{×}5+36\text{×}4-36\text{×}6+36\text{×}4\)

\(=36\text{×}\left(5+4-6+4\right)=36\text{×}7=252\)

\(=245\times5=1225\)

8820 : 36 x 5 = 245 x 5 = 1225 

1225

Ta có: 36x5-70+35 = 36x5-14x5+7x5 = (36-14+7)x5 = 29x5 = 145

A = \(\dfrac{2,4\times1994\times2+1,6\times3396\times3+1,2\times4010\times4}{3+7+11+15+...+95+99-275}\)

A = \(\dfrac{\left(2,4\times2\right)\times1994+\left(1,6\times3\right)\times\left(1,2\times4\right)\times4010}{\left(3+7+11+15+...+95+99\right)-275}\)

A = \(\dfrac{4,8\times1994+4,8\times3396+4,8\times4010}{\left(3+7+11+15+...+95+99\right)-275}\)

A = \(\dfrac{4,8\times\left(1994+3396+4010\right)}{\left(3+7+11+15+...+95+99\right)-275}\)

Đặt B = 3 + 7 + 11 +...+ 95+ 99

Dãy số trên là dãy số cách đều với khoảng cách là: 7 - 3 = 4

Số số hạng của dãy số trên là: (99 - 3): 4 + 1 = 25 

Tổng B là: (99 + 3) \(\times\)25 : 2 = 1275

A = \(\dfrac{4,8\times\left(1994+3396+4010\right)}{1275-275}\)

A = \(\dfrac{4,8\times10000}{1000}\)

A =  4,8 \(\times\) 10
A = 48 

\(=\dfrac{7}{19}\cdot\dfrac{5}{13}+\dfrac{7}{19}\cdot\dfrac{8}{13}-3\cdot\dfrac{7}{19}=\dfrac{7}{19}\cdot\left(\dfrac{5}{13}+\dfrac{8}{13}-3\right)=-2\cdot\dfrac{7}{19}=-\dfrac{14}{19}\)

64.(75+24+1)

=64.100

=6400

 64 x 75 + 24 x 64 + 64

 64 x 75 + 24 x 64 + 64 + 1

<75 +24+1>x64

100x64

6400

= 64(75+24+1)

=64*100

=6400

\(\dfrac{7}{3}-\dfrac{13}{9}+3+\dfrac{4}{9}\\ =\left(\dfrac{7}{3}+3\right)+\left(\dfrac{4}{9}-\dfrac{13}{9}\right)\\ =\dfrac{16}{3}+\left(\dfrac{-9}{9}\right)\\ =\dfrac{16}{3}-1\\ =\dfrac{13}{3}\)

\(=\dfrac{7}{3}-\left(\dfrac{13}{9}-\dfrac{4}{9}\right)+3=\dfrac{7}{3}-1+3=\dfrac{7}{3}+2=\dfrac{13}{3}\)