Bài làm:

\(M=\left(12x^8+8x^2+6x-7\right)-\left(12x^8+2x-8\right)+\left(5-8x^2\right)\)

\(M=4x+6\)

\(M=4x+6\)

Học tốt

a) 3^x = 3^-12. 3^-15 . 3³²  =3⁵

x = 5

b) 2^x = 2⁹ .2^-30. 2⁹ = 2^-12

x = -12

c) 2^x = 2¹⁴ / 2⁹ = 2⁵

x = 5

\(\frac{2}{\left(x+2\right)\left(x+4\right)}+\frac{4}{\left(x+4\right)\left(x+8\right)}+\frac{6}{\left(x+8\right)\left(x+14\right)}=\frac{x}{\left(x+2\right)\left(x+14\right)}\)

\(\Rightarrow\frac{1}{x+2}-\frac{1}{x+4}+\frac{1}{x+4}-\frac{1}{x+8}+\frac{1}{x+8}-\frac{1}{x+14}=\frac{x}{\left(x+2\right)\left(x+14\right)}\)

\(\Rightarrow\frac{1}{x+2}-\frac{1}{x+14}=\frac{x}{\left(x+2\right)\left(x+14\right)}\)

\(\Rightarrow\frac{x+14}{\left(x+2\right)\left(x+14\right)}-\frac{x+2}{\left(x+2\right)\left(x+14\right)}=\frac{x}{\left(x+2\right)\left(x+14\right)}\)

\(\Rightarrow\frac{x+14-x+2}{\left(x+2\right)\left(x+14\right)}=\frac{x}{\left(x+2\right)\left(x+14\right)}\)

\(\Rightarrow\frac{12}{\left(x+2\right)\left(x+14\right)}=\frac{x}{\left(x+2\right)\left(x+14\right)}\)

=> x = 12

1, đặt k 2, nhân chéo

Áp dụng tính chất dãy tỉ số bằng nhau 

ta có ; \(\frac{x^2}{4}=\frac{y}{2}=\frac{x^2-3y}{4-\left(3.2\right)}=\frac{-8}{-2}=4.\)

\(\Rightarrow\frac{x^2}{4}=4\Rightarrow x^2=16\Rightarrow x=\pm4\)

\(\Rightarrow\frac{y}{2}=4\Rightarrow y=8\)

làm cho 1 cái những cái sau tương tự mà lm nha bạn

\(\frac{x}{5}=-\frac{6}{7}\)

\(=>7x=-6\cdot5\)

\(7x=-30\)

\(x=-\frac{30}{7}\)

\(\frac{x}{2}=-\frac{8}{-x}\)

\(=>\frac{x}{2}=\frac{8}{x}\)

\(=>xx=8\cdot2\)

\(x^2=16\)

\(=>x\in\left\{-4;4\right\}\)

a: |x-1/2|=7/2

=>x-1/2=7/2 hoặc x-1/2=-7/2

=>x=4 hoặc x=-3

b: \(x:\dfrac{3}{8}+\dfrac{5}{8}=x\)

=>8/3x-x=-5/8

=>5/3x=-5/8

hay x=-5/8:5/3=-5/8x3/5=-15/40=-3/8

c: \(\dfrac{5}{6}-\left|x-\dfrac{1}{2}\right|=\dfrac{15}{18}=\dfrac{5}{6}\)

=>|x-1/2|=0

=>x-1/2=0

hay x=1/2

e: \(\left(5x-3\right)^2-\dfrac{1}{64}=0\)

=>(5x-3)²=1/64

=>5x-3=1/8 hoặc 5x-3=-1/8

=>5x=25/8 hoặc 5x=23/8

=>x=5/8 hoặc x=23/40

a: \(\Leftrightarrow4^x\left(\dfrac{3}{2}+\dfrac{5}{3}\cdot4^2\right)=4^8\left(\dfrac{3}{2}+\dfrac{5}{3}\cdot4^2\right)\)

=>4^x=4^8

=>x=8

b: \(\Leftrightarrow2^x\cdot\dfrac{1}{2}+2^x\cdot2=2^{10}\left(2^2+1\right)\)

=>2^x=2^11

=>x=11

c: =>1/6*6^x+6^x*36=6^15(1+6^3)

=>6^x=6*6^15

=>x=16

d: \(\Leftrightarrow8^x\left(\dfrac{5}{3}\cdot8^2-\dfrac{3}{5}\right)=8^9\left(\dfrac{5}{3}\cdot8^2-\dfrac{3}{5}\right)\)

=>x=9

Bài 1:

a) \(\left(2-3x\right)-\left(5x+8\right)=15x\)

\(\Leftrightarrow2-3x-5x-8-15x=0\)

\(\Leftrightarrow-23x-6=0\)

\(\Leftrightarrow x=\frac{-6}{23}\)

Vậy...

b) \(3\left(x-3\right)-2\left(8-x\right)=6\)

\(\Leftrightarrow3x-9-16+2x-6=0\)

\(\Leftrightarrow5x-31=0\)

\(\Leftrightarrow x=\frac{31}{5}\)

Vậy...

c) \(\frac{7-x}{2}-\frac{2x-3}{4}=\frac{x+2}{8}-\frac{-1}{2}\)

\(\Leftrightarrow4\left(7-x\right)-2\left(2x-3\right)=x+2+4\)

\(\Leftrightarrow28-4x-4x+6-x-6=0\)

\(\Leftrightarrow-9x+28=0\)

\(\Leftrightarrow x=\frac{28}{9}\)

Vậy...

d) \(x^2\cdot\left(-4x\right)+3=0\)

\(\Leftrightarrow-4x^3=-3\)

\(\Leftrightarrow x^3=\frac{3}{4}\)

\(\Leftrightarrow x=\sqrt[3]{\frac{3}{4}}\)

Vậy...

a) \(\left(2-3x\right)-\left(5x+8\right)=15x\)

\(\Leftrightarrow2-3x-5x-8=15x\)

\(\Leftrightarrow15x+3x+5x=2-8\)

\(\Leftrightarrow23x=-6\)

\(\Leftrightarrow x=-\frac{6}{23}\)

Vậy : \(x=-\frac{6}{23}\)

b) \(3\left(x-3\right)-2\left(8-x\right)=6\)

\(\Leftrightarrow3x-9-16+2x=6\)

\(\Leftrightarrow5x=6+9+16=41\)

\(\Leftrightarrow x=\frac{41}{5}\)

Vậy : \(x=\frac{41}{5}\)

Ta có : x(x - 2) - x(x - 1) - 15 = 0

<=> x² - 2x - x² + x - 15 = 0

<=> -x - 15 = 0

=> -x = 15

=> x = -15