a) 2021 + 2022 + 2023 + 2024 + 2025 + 2026 + 2027 + 2028 + 2029

= (2021 + 2029) + (2022 + 2028) + (2023 + 2027) + (2024 + 2026) + 2025

= 4050 + 4050 + 4050 + 4050 + 2025

= 4050.4 + 2025

= 16 200 + 2025 

= 18 225

b)

a) 2021+2022+2023+2024+2025+2026+2027+2028+2029
= (2021+2029)+(2022+2028)+(2023+2027)+(2024+2026)+2025
= 4050+4050+4050+4050+2025
= 18225

b) 30.40.50.60
= 10.3.10.4.10.5.10.6
= (10.10.10.10).(3.4.5.6)
= 1000.360
= 3600000

( x + 70 ) : 14 - 40 = (32 . 15 ) : 2

( x + 70 ) : 14 - 40 = 240

( x + 70 ) : 14 = 240 + 40 = 280

x + 70 = 280 x 14 = 3920

x = 3920 - 70 

x = 3850

Vậy x = 3850.

(x+70):14-40=(32.15):2

(x+70):14-40=480;2

(x+70):14-40=240

(x+70);14=240+40

(x+70):14=280

(x+70)=280.14

(x+70)=3360

x=3360-70

x=3290

x=1:(1/15+1/35+1/63)

x=9

Vậy x=9

a) \(5+3^{x+1}=86\)

\(=>3^{x+1}=86-5\)

\(=>3^{x+1}=81=3^4\)

\(=>x+1=4\) ( cùng cơ số )

\(=>x=4-1\)

\(=>x=3\)

b) \(15:\left(x+2\right)=\left(3^3+3\right):10\)

\(=>15:\left(x+2\right)=\left(27+3\right):10\)

\(=>15:\left(x+2\right)=30:10=3\)

\(=>x+2=15:3\)

\(=>x+2=5\)

\(=>x=5-2\)

\(=>x=3\)

c) \(\left(9x+2\right).4=80\)

\(=>9x+2=80:4\)

\(=>9x+2=20\)

\(=>9x=20-2\)

\(=>9x=18\)

\(=>x=18:9\)

\(=>x=2\)

d) \(\left(245-x\right)+7^2=14\)

\(=>\left(245-x\right)+14=14\)

\(=>245-x=14-14\)

\(=>245-x=0\)

\(=>x=245-0\)

\(=>x=245\)

?

a)300

b)374

c)4747

d)4530

e)2250

g)123123

Đây là toán lớp 4

a) 300

b) 374

c) 4747

d) 4530

e) 2250

g) 123123

a) 25 x 12 = 25 x 4 x 3 = 100 x 3 = 300

b) 34 x 11 = 34 x ( 10 + 1 ) = 34 x 10 + 34 x1 = 340 + 34 = 374

c) 47 x 101 = 47 x ( 100 + 1 ) = 47 x 100 + 47 x 1 = 4700 + 47 = 4747

d) 15 x 302 = 15 x ( 300 + 2 ) = 15 x 300 + 15 x 2 = 4500 + 30 = 4530

g) 123 x 1001 = 123 x ( 1000 + 1 ) = 123 x 1000 +123 x 1 = 123000 + 123 = 123123

\(a,TH1:x-2021=0=>x=2021\)

\(Th2:x-2022=0=>x=2022\)

Vậy \(x\in\left\{2021;2022\right\}\)

\(b,x\left(8-5\right)=1080\)

\(x.3=1080\)

\(x=360\)

\(c,x^3=216< =>6^3=216=>x=3\)

\(d,5^5=3125\)

a)  ( x- 2021) * ( x- 2022) = 0

=>  \(\orbr{\begin{cases}x-2021=0\\x-2022=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=2021\\x=2022\end{cases}}}\)

b)  b. 8x - 5x = 2022

=>  3x  =  2022

=>  x  =   674

c)  \(5\cdot x^3=1080\)

=>  \(x^3=216\)

=>  \(x^3=6^3\)

=>   x  =  6

d)   \(5^x=3125\)

=>    \(5^x=5^5\)

=>  x    =  5

* \(20+65.4=\left(x+75\right):5+30\)

\(\Leftrightarrow20+260-30=\frac{x}{5}+\frac{75}{5}\)

\(\Leftrightarrow20+260-30-\frac{75}{5}=\frac{x}{5}\)

\(\Leftrightarrow235=\frac{x}{5}\Rightarrow x=235.5=1175\)

* \(2248:\left[119-\left(x-6\right)\right]=24\)

\(\Leftrightarrow2248:\left(119-x+6\right)=24\)

\(\Leftrightarrow2248:\left(125-x\right)=24\)

A mình lỡ tay, để mình tính tiếp nhá!

\(\Leftrightarrow125-x=2248:24\Leftrightarrow125-x=\frac{281}{3}\Rightarrow-x=\frac{94}{3}\Rightarrow x=-\frac{94}{3}\)(bài này mình thấy sai sai sao á, nếu mình làm sai thì thông cảm cho mình nhé!

* \(\left(x+70\right):14-40=\left(32.15\right):2\)

\(\Leftrightarrow\left(x+70\right):14=480:2+40\)

\(\Leftrightarrow\frac{x}{14}+5=280\Leftrightarrow\frac{x}{14}=275\Rightarrow x=3850\)

* \(x-4867=\left(175.2050.70\right):25+23\)

\(\Leftrightarrow x-4867-23=\left(175:25\right).\left(2050:25\right).\left(70:25\right)\)

\(\Leftrightarrow x-4890=7.82.\frac{14}{5}\)

\(\Leftrightarrow x-4890=\frac{8036}{5}\Rightarrow x=\frac{8036}{5}+4890=\frac{32486}{5}\)(bài này mình thấy hình như cũng có cái gì đó sai sai luôn hihi!)

=24 nha

a, \(\frac{2}{3}\).\(\frac{15}{17}\)+\(\frac{2}{3}\).\(\frac{2}{17}\)

= \(\frac{2}{3}\).( \(\frac{15}{17}\)+ \(\frac{2}{17}\))

= \(\frac{2}{3}\). 1

=\(\frac{2}{3}\)

b,\(\frac{20}{19}\):\(\frac{3}{7}\)- \(\frac{1}{19}\): \(\frac{3}{7}\)

= ,\(\frac{20}{19}\).\(\frac{7}{3}\)- \(\frac{1}{19}\).\(\frac{7}{3}\)

= \(\frac{7}{3}\).(\(\frac{20}{19}\)-\(\frac{1}{19}\))

=\(\frac{7}{3}\).1

=\(\frac{7}{3}\)