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a. 8x+2x =25. 2 mũ 2
8x+2x=100
(8+2)x=100
10x=100
x=100:10
x=10
b.5x+2x=35
(5+2)x=35
7x=35
x=35:7
x=5

a) 8x + 2x = 25 . 22
8x + 2x = 100
( 8 + 2 )x = 100
10x = 100
x = 100 : 10
x = 10
b) 5x + 2x = 35
( 5 + 2 )x = 35
7x = 35
x = 35 : 7
x = 5
c) 5x + x = 150 : 2 + 3
5x + x = 75 + 3
5x + x = 78
( 5 + 1 )x = 78
6x = 78
x = 78 : 6
x = 13
d) 6x + x = 511 : 59 + 31
6x + x = 52 + 31
6x + x = 25 + 3
6x + x = 28
( 6 + 1 )x = 28
7x = 28
x = 28 : 7
x = 4
e) 5x + 3x = 36 : 33 . 4 + 12
5x + 3x = 33 . 4 + 12
5x + 3x = 27 . 4 + 12
5x + 3x = 108 + 12
5x + 3x = 120
( 5 + 3 )x = 120
8x = 120
x = 120 : 8
x = 15

\(2x-8x^2=0\Rightarrow2x\left(1-4x\right)=0\Rightarrow\orbr{\begin{cases}2x=0\\1-4x=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=\frac{1}{4}\end{cases}}}\)
\(x-x^2=0\Rightarrow x\left(1-x\right)=0\Rightarrow\orbr{\begin{cases}x=0\\1-x=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=1\end{cases}}}\)
Cn lại lm tương tự nha e!
=.= hok tốt!!

3\(x^2\).(5\(x\) + 1) + 6\(x^3\).(5\(x\) + 2) = 9\(x^3\) .(5\(x\) + 3)
15\(x^3\) + 3\(x^2\) + 30\(x^4\) + 12\(x^3\) = 45\(x^4\) + 27\(x^3\)
(15\(x^3\) + 12\(x^3\)) + 3\(x^2\) + 30\(x^4\) - 45\(x^4\) - 27\(x^3\) = 0
27\(x^3\) + 3\(x^2\) - 15\(x^4\) - 27\(x^3\) = 0
3\(x^2\) - 15\(x^4\) = 0
3\(x^2\).(1 - 5\(x^2\)) = 0
\(\left[{}\begin{matrix}x^2=0\\1-5x^2=0\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=0\\5x^2=1\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=0\\x=\mp\dfrac{\sqrt{5}}{5}\end{matrix}\right.\)


1,7x=5^2+3
7x=28
x=28:7
x=4
mấy câu còn lại tương tự như vậy thôi,5x+3x=8x;4x+2x=6x;5x+x=6x

\(5x+2x=6^2-5^0\Leftrightarrow5x+2x=6^2-1\)
\(\Leftrightarrow5x-2x=36-1\Leftrightarrow5x-2x=35\Leftrightarrow x\left(5+2\right)=35\)
\(\Leftrightarrow7x=35\Leftrightarrow x=35:7\Leftrightarrow x=5\)
\(5x+x=150:2+3\Leftrightarrow5x+x=75+3\)
\(\Leftrightarrow5x+x=78\Leftrightarrow x\left(5+1\right)=78\Leftrightarrow x6=78\)
\(\Leftrightarrow x=78:6\Leftrightarrow x=13\)
a) 5x + 2x = 62 - 50
7x = 35 => x = 5
b) 5x + x = 150 : 2 + 3
6x = 78 => x = 13
c) 6x + x = 511 : 59 + 31
7x = 28 => x = 4
d) 5x + 3x = 36 : 33 x 4 + 12
8x = 120 => x = 15
e) 4x + 2x = 68 - 219 : 216
6x = 60 => x = 10
f) 5x + x = 39 - 311 : 39
6x = 30 => x = 5
g) 7x - x = 521 : 519 + 3 x 22 - 70
6x = 36 => x = 6
h) 7x - 2x = 617 : 615 + 44 : 11
5x = 40 => x = 8
Khi \(x+3=1\Leftrightarrow x=-2\)
Thay \(x=-2\) vào B ta có
\(B=5.\left(-2\right)^2+6.\left(-2\right)-2\)
\(B=6\)