4+6+8+...+x=928

Số số hạng là \(\dfrac{x-4}{2}+1=\dfrac{x-4+2}{2}=\dfrac{x-2}{2}\)

Tổng của dãy số là \(\dfrac{\left(x+4\right)\left(x-2\right)}{2}\cdot\dfrac{1}{2}=\dfrac{\left(x+4\right)\left(x-2\right)}{4}\)

Theo đề, ta có: \(\dfrac{\left(x+4\right)\left(x-2\right)}{2}=928\)

=>\(\left(x+4\right)\left(x-2\right)=928\cdot2=1856\)

=>\(x^2+2x-8-1856=0\)

=>\(x^2+2x-1864=0\)

=>\(x^2+2x+1-1865=0\)

=>\(\left(x+1\right)^2=1865\)

=>\(\left[{}\begin{matrix}x+1=\sqrt{1865}\\x+1=-\sqrt{1865}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{1865}-1\left(loại\right)\\x=-\sqrt{1865}-1\left(loại\right)\end{matrix}\right.\)

Vậy: \(x\in\varnothing\)

1b - 2c - 3b - 4a - 5b - 6c - 7b - 8c - 9c

1.I find ____ a useful sport for my health

   a.swim       b.swimming           c.swimmer           d.swam

2.when my father retired,he took_____ golf as a hobby to stay health

   a.on           b.at             c.up          d.in

3.Sometimes a rainbow_____after the rain.

    a.appear          b.appears          c.not appear            d.doesn't appears

4.Lan has the same hobby____Nga

a.as           b.for             c.of                d.on

5.My father's hobby is ____stamps

a.collect           b.collecting         c.collector             d.collection

6.I think collecting old bowls is a very____hobby

a.bore          b.bored         c.boring         boreness

7.My uncle often gives me presents _____special occasions

a.in           b.on             c.of             d.for

8.Do you háve a____hobby?

a.difficulty            b.difficulties          c.difficult           d.differ

9.These gifts are made____eggshells

a.to          b.for             c.of              d.at

Số số hạng dãy số đó là:(2024-2):2+1=1011

Tổng dãy số là:(2 + 2024) * 1012 / 2 = 1.026.028

Tổng là 1.026.028

(nêu tớ có tính sai thì cho xl trước nhé =(( )

Số số hạng của tổng \(2+4+6+8+...+2022+2024\) là:

\(\left(2024-2\right):2+1=1012\) (số)

Tổng \(2+4+6+8+...+2022+2024\) bằng:

\(\left(2024+2\right)\times1012:2=1025156\)

\(a.\left(x-2\right)\left(x^2+x-1\right)-x\left(x^2-1\right)\\ =\left(x^3+x^2-x-2x^2-2x+2\right)-\left(x^3-x\right)\\ =x^3-x^2-3x+2-x^3+x\\ =-x^2-2x+2\\ b.\left(2x-9\right)\left(2x+9\right)-4x^2\\ =\left[\left(2x\right)^2-9^2\right]-4x^2\\ =4x^2-81-4x^2\\ =-81\\ c.2x^2+3\left(x-1\right)\left(x-1\right)\\ =2x^2+3\left(x-1\right)^2\\ =2x^2+3\left(x^2-2x+1\right)\\ =2x^2+3x^2-6x+3\\ =5x^2-6x+3\)

a; (\(x\) - 2)(\(x^2\) + \(x\) - 1) - \(x\)(\(x^2\) - 1)

 =   \(x^3\) + \(x^2\) - \(x\) - 2\(x^2\) - 2\(x\) + 2 - \(x^3\) + \(x\)

=    (\(x^3\) - \(x^3\)) - ( 2\(x^2\) - \(x^2\)) - (\(x\) + 2\(x\) - \(x\)) + 2

= 0 - \(x^2\) - (3\(x\) - \(x\)) + 2

= - \(x^2\) - 2\(x\) + 2

283-2.x=84

       2.x=283-84

       2.x=199 

          X=199:2

           X = 99,5

\(30-3\left(x-2\right)=35\\ 3\left(x-2\right)=30-35\\ 3\left(x-2\right)=-5\\ x-2=-\dfrac{5}{3}\\ x=2-\dfrac{5}{3}\\ x=\dfrac{6}{3}-\dfrac{5}{3}\\ x=\dfrac{1}{3}\)

\(-\dfrac{3}{11}.\dfrac{5}{7}+\dfrac{5}{7}.-\dfrac{8}{11}+\dfrac{19}{7}\)

`=` \(\dfrac{5}{7}.\left(\dfrac{-3}{11}+\dfrac{-8}{11}\right)+\dfrac{19}{7}\)

`=` \(\dfrac{5}{7}.\dfrac{-11}{11}+\dfrac{19}{7}\)

`=` \(\dfrac{5}{7}.\left(-1\right)+\dfrac{19}{7}\)

`=` \(-\dfrac{5}{7}+\dfrac{19}{7}\)

`=` \(\dfrac{14}{7}\)

`=  2`

\(2^{16}\) `=` \(2^{13+3}=2^{13}.2^3=2^{13}.8>2^{13}.7\)

Vậy \(2^{16}\) `>` \(2^{13}\) `. 7`

27⁵ và 243³