407 - [( 190 - 170 ) : 4 + 9 ] : 2

= 407 - [ 20 : 4 + 9 ] : 2

= 407 - [ 5 + 9 ] : 2

= 407 - 14 : 2

= 407 - 7

= 400

407 - [ (190 - 170 ): 5 + 9] : 2

407 - [ 20 : 5 + 9]:2

407 - [ 4 + 9]:2

= 407 - 6,5

= 400,5

(23.36-17.36):36

=(36.(23-17)):36

= (36.6):36

=216:36

=6

=407-[20:4+9]:2

=407-[5+9]:2

=407-14:2

=407-7

=400

đây nha:

=407-[20:4+9]:2

=407-[5+9]:2

=407-14:2

=407-7

=400

a: \(\dfrac{7}{4}-\dfrac{11}{8}+\dfrac{1}{2}\)

\(=\dfrac{14-11+4}{8}\)

\(=\dfrac{7}{8}\)

b: \(\dfrac{3}{16}+\dfrac{7}{30}\cdot\dfrac{40}{36}\)

\(=\dfrac{3}{16}+\dfrac{7}{36}\cdot\dfrac{40}{30}\)

\(=\dfrac{3}{16}+\dfrac{7}{36}\cdot\dfrac{4}{3}\)

\(=\dfrac{3}{16}+\dfrac{7}{27}=\dfrac{81+112}{432}=\dfrac{193}{432}\)

c: \(\left(\dfrac{9}{2}-\dfrac{15}{4}\right):\dfrac{21}{12}\)

\(=\left(\dfrac{18}{4}-\dfrac{15}{4}\right):\dfrac{7}{4}\)

\(=\dfrac{3}{4}\cdot\dfrac{4}{7}=\dfrac{3}{7}\)

=(36.(23-17)):36

=36.6:36

=(36:36).6

=1.6

= 6

+)(23.36-17.36):36

=[36.(23-17)]:36

=36.6:36

A = 13/21.2/11 + 13/21.9/11 + 8/21
= (13/21) + (13/21) + (8/21)
= (13 + 13 + 8)/21
= 34/21

B = (1 - 1/5)(1 - 2/5)(1 - 3/5)...(1 - 9/5)
= (4/5)(3/5)(2/5)(1/5)(0/5)(-1/5)(-2/5)(-3/5)(-4/5)
= 0

C = (1 - 1/2)(1 - 1/3)(1 - 1/4)...(1 - 1/50)
= (1/2)(2/3)(3/4)(4/5)...(49/50)
= 1/50

D = (2^2/1.3) * (3^2/2.4) * (4^2/3.5) * (5^2/4.6) * (6^2/5.7)
= (4/3) * (9/8) * (16/15) * (25/23) * (36/35)
= 0.979

cho x chạy từ 2 đến 20, công thức X^2/(x-1)(x+1) tổng là: 16549/840

đăng ít thôi bạn đăng nhiều thế mới nhìn vào đã thấy chóng mặt huống chi là giải

2: \(=16\cdot38-16\cdot2-38\cdot16+38=-32+38=6\)

3: \(=6-7+4-3=10-10=0\)

4: \(=-125\left(26-36\right)=-125\cdot\left(-10\right)=1250\)

5: \(=5^3-5^3=0\)

6: \(=24\left(-125+225\right)=100\cdot24=2400\)

7: =21(135+65)-200

=200*21-200

=200*20=4000

8: =42+58-19+19=100