\(x.[\left(-2x\right)^2+5x]=16\)

\(\Rightarrow x.[\left(-4x\right)+5x]=16\)

\(\Rightarrow x.x=16\)

\(\Rightarrow2x=16\Rightarrow x=8\)

Vay \(x=8\)

a) 2x + 5 < 0 => 2x < - 5 => x < -2,5

b) -4 - 5x > 0 => -4 > 5x => -0,8 > x

c) -7x + 3 < 0 => -7x < -3 => x > 3/7

d) x - 7 > 0 => x > 7

e) -3 + 4x > 0 => 4x > 3 => x > 0,75

\(a,2x+5< 0\)                                                        \(b,-4-5x>0\)

\(\Rightarrow2x< -5\)                                                          \(\Rightarrow-4>5x\)

\(\Rightarrow x< -\frac{5}{2}\)                                                          \(\Rightarrow x< -\frac{4}{5}\)

\(c,-7x+3< 0\)                                                   \(d,x-7>0\)

\(\Rightarrow-7x< -3\)                                                      \(\Rightarrow x>7\)

\(\Rightarrow x>\frac{3}{7}\)

\(e,-3+4x>0\)

\(\Rightarrow4x>3\)

\(\Rightarrow x>\frac{3}{4}\)

\(\left(\frac{5}{2.7}+\frac{5}{7.12}+\frac{5}{17.22}+\frac{5}{22.27}+\frac{5}{27.32}\right)x=945\)

\(\left(\frac{7-2}{2.7}+\frac{12-7}{7.12}+\frac{17-12}{12.17}+\frac{22-17}{17.22}+\frac{27-22}{22.27}+\frac{32-27}{27.32}\right)x=945\)

\(\left(\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{12}+...+\frac{1}{27}-\frac{1}{32}\right)x=945\)

\(\left(\frac{1}{2}-\frac{1}{32}\right)x=945\Leftrightarrow\frac{15}{32}x=945\Leftrightarrow x=945:\frac{15}{32}=2016\)

\(a,\Rightarrow2x^2-18x-2x^2=0\\ \Rightarrow-18x=0\Rightarrow x=0\\ b,\Rightarrow2x^2-5x-12+x^2-7x+10=3x^2-17x+20\\ \Rightarrow5x=22\Rightarrow x=\dfrac{22}{5}\)

\(\dfrac{3}{x}=\dfrac{1}{y}=\dfrac{6}{2}\)

\(\Rightarrow\dfrac{3}{x}=\dfrac{1}{y}=3\)

\(\Rightarrow\left\{{}\begin{matrix}x=1\\y=\dfrac{1}{3}\end{matrix}\right.\)

x = 1

y = 1/3

x = 1 

y = 1/3. 

đặt A=(x+1)+(X+2)+(x+3)+....+(x+99)

=> A= x+1+x+2+x+3+....+x+100

=x+x+x+x+...+x+(1+2+3+4+..+99)( có 99x)

=> 99x+4950=0

=> 99x=-4950

=> x=-50

2|5x−3|−2x=14 
Xét 5x−3≥0 <=> x≥35
 => 2(5x−3)−2x=14
<=> 10x−6−2x=14
<=> 8x=20
<=> x=208=52 (thoả mãn)
Xét 5x−3<0 => x<35
 => 2(3−5x)−2x=14
<=> 6−10x−2x=14
<=> −12x=8
<=> x=−812=−23 (thoả mãn)

èo... bạn ko viết dấu nhân,mãi mk mới hiểu !!

(52-2):2+1=26

(52+2)*26:2=741

1092-741=351

351:26=13,5

       Đ/s: 13,5

Không biết đúng không đâu,đừng làm theo nha,ngu cả đời đấy,kb nha

15 nha các cậu,đúng 100000000000000000000% luôn,kiểm tra rùi ,hihi ,sory nha

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