a,= (45-35)+(-28+27+11)-6=10+10-6=14

b,=(305-105)+(-246+546)=200+300=500

c,= (435-415)+(-43-57)+(-483+383)=20-100-100=-180

d,=(1316-1216)+(317-315-85)= 100-83= 17

92 – 7.(3x + 52)= 8⁶ : 8⁴

92-21x-364=8^6-4

92-21x-364=8²

92-21x-364=64

-21x=64-92+364

-21x=336

x=336:(-21)

x=-16

\(92-7.\left(3x+52\right)=8^6:8^4\\ \Leftrightarrow92-21x-364=8^2\\ \Leftrightarrow-21x=64-92+7.52\\ \Leftrightarrow-21x=336\\ \Leftrightarrow x=\dfrac{336}{-21}=-16\)

\(92-7.\left(3x+52\right)=8^6:8^4\)

\(92-21x-364=64\)

\(-21x=64+364-92\)

\(-21x=336\)

\(x=\dfrac{336}{-21}\)

\(x=-16\)

\(a,=2^3\left(17-14\right)=2^3\cdot3=24\\ b,=80-\left(130-8^2\right)=80-\left(130-64\right)=80-66=14\)

2A=1/2+1/6+1/12+1/20+1/30+1/42

    =1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7

    =1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7

    =1-1/7

    =6/7

a: Số số hạng là 100-50+1=51 số

Tổng là (100+50)*51/2=51*75=3825

b: Số số hạng là (223-21):2+1=102(số)

Tổng là (223+21)*102/2=12444

c: Số số hạng là (72-12):4+1=16(số)

Tổng là (72+12)*16/2=672

d: Số số hạng là (124-4):6+1=21(số)

Tổng là (124+4)*21/2=1344

ta có : (ghi lại đề)

=6+12+18+24+30/3+6+9+12+15

=2*(3/3+6/6+9/9+12/12+15/15)

=2*(1+1+1+1+1)

=2*5=10

chúc main học tốt nhé

hi

a) \(153^2-53^2=\left(153-53\right)\left(153+53\right)=100.206=20600\)

b)

\(\left(2020^2-2019^2\right)+\left(2018^2-2017^2\right)+...+\left(2^2-1^2\right)\\ =\left(2020+2019\right)\left(2020-2019\right)+\left(2018+2017\right)\left(2018-2017\right)+...+\left(2+1\right)\left(2-1\right)\\ =2020+2019+2018+2017+...+2+1\\ =\dfrac{\left(2020+1\right)2020}{2}=2041210\)

Lời giải:

a. $153^2-53^2=(153-53)(153+53)=100.206=20600$

b. 

$2020^2-2019^2+2018^2-2017^2+...+2^2-1^2$

$=(2020^2-2019^2)+(2018^2-2017^2)+...+(2^2-1^2)$

$=(2020-2019)(2020+2019)+(2018-2017)(2018+2017)+...+(2-1)(2+1)$

$=2020+2019+2018+2017+...+2+1$

$=\frac{2020.2021}{2}=2041210$

a) 153²-53²=(153-53)(153+53)=100.206=20600

a) Ta có: \(A=\dfrac{37^3+12^3}{49}-37\cdot12\)

\(=\dfrac{\left(37+12\right)\left(37^2-37\cdot12+12^2\right)}{49}-37\cdot12\)

\(=37^2-2\cdot37\cdot12+12^2\)

\(=\left(37-12\right)^2\)

\(=25^2=625\)

\(\dfrac{9}{2}+\left(x-\dfrac{3}{4}\right)=\dfrac{25}{4}\\x-\dfrac{3}{4}=\dfrac{25}{4}-\dfrac{9}{2}\\ x-\dfrac{3}{4}=\dfrac{7}{4}\\ x=\dfrac{7}{4}+\dfrac{3}{4}\\ x=\dfrac{5}{2} \)

5/2

\(\dfrac{5}{2}\)