\(\left(2x+3\right)\left(x-4\right)+\left(x-5\right)\left(x-2\right)=\left(3x-5\right)\left(x-4\right)\)

\(\Leftrightarrow\left(2x^2-5x-12\right)+\left(x^2-7x+10\right)=3x^2-17x+20\)

\(\Leftrightarrow3x^2-12x-2-3x^2+17x-20=0\)

\(\Leftrightarrow5x-22=0\)

\(\Leftrightarrow x=\frac{22}{5}\)

a) (x-2)³+6(x+1)²-x³+12=0

\(\Rightarrow\)x³-6x²+12x-8+6(x²+2x+1)-x³+12=0

\(\Rightarrow\)x³-6x²+12x-8+6x²+12x+6-x³+12=0

\(\Rightarrow\)24x+10=0

\(\Rightarrow\)24x=-10

\(\Rightarrow\)x=\(\dfrac{-10}{24}=\dfrac{-5}{12}\)

b)(x-5)(x+5)-(x+3)²+3(x-2)²=(x+1)²-(x-4)(x+4)+3x²

\(\Rightarrow\)x²-25-(x²+6x+9)+3(x²-4x+4)=x²+2x+1-(x²-16)+3x²

\(\Rightarrow\)x²​-25-x²-6x-9+3x²-12x+12=x²+2x+1-x²+16+3x²

\(\Rightarrow\)3x²-18x-22=3x²+2x+17

\(\Rightarrow\)3x²-18x-22-3x²-2x-17=0

\(\Rightarrow\)-20x-39=0

\(\Rightarrow\)-20x=39

\(\Rightarrow\)x=\(-\dfrac{39}{20}\)

a. \(x\left(x^2-25\right)-\left(x^3-2x^2+4x+2x^2-4x+8\right)=17\)

\(x^3-25x-\left(x^3+8\right)=17\)

\(x^3-25x-x^3-8=17\)

\(-25x=25\)

\(x=-1\)

c. \(6x^2-\left(6x^2-4x+15x-10\right)=7\)

\(6x^2-6x^2-11x+10=7\)

\(-11x=-3\)

\(x=\frac{3}{11}\)

\(a,5\left(3x+5\right)-4\left(2x-3\right)=5x+8\left(2x+12\right)+1\)

\(\Rightarrow5\left(3x+5\right)-4\left(2x-3\right)-5x-8\left(2x+12\right)-1=0\)

\(\Rightarrow15x+25-8x+12-5x-16x-96-1=0\)

\(\Rightarrow-14x-60=0\)

\(\Rightarrow-14x=60\) \(\Rightarrow x=-\frac{60}{14}=\frac{-30}{7}\)

\(b,\left(2x+3\right)\left(x-4\right)-\left(3x-5\right)\left(x-4\right)=\left(5-x\right)\left(x-2\right)\)

\(\Rightarrow2x^2+3x-8x-12-3x^2+5x+12x-20=5x-x^2-10+2x\)

\(\Rightarrow-x^2+12x-32=7x-x^2-10\)

\(\Rightarrow-x^2+12x-32-7x+x^2+10=0\)

\(\Rightarrow5x-22=0\)

\(\Rightarrow5x=22\Rightarrow x=\frac{22}{5}\)

a) 5(3x+5)-4(2x-3) = 5x+8(2x+12)+1

15x + 25 - 8x + 12 = 5x + 16x + 96 + 1

15x - 8x - 5x - 16x = 96 + 1 - 25 - 12

-14x = 60

x = \(\frac{60}{-14}\)

x = \(-\frac{30}{7}\)

b) (2x+3)(x-4)-(3x-5)(x-4) = (5-x).(x-2)

(x - 4)(2x + 3 - 3x +5) = 5x - 10 - x² + 2x

(x - 4)[(2x - 3x) + (3 + 5)] = 5x - 10 - x² + 2x

(x - 4)(-x + 8) = 5x - 10 - x² + 2x

-x² + 8x + 4x - 32 = 5x - 10 - x² + 2x

(-x² + x²) + (8x + 4x - 5x - 2x) = -10 + 32

5x = 22

x = \(\frac{22}{5}\) 

C

\(\Rightarrow x^2-16-x^2+3x=5\)

\(\Rightarrow3x=21\Rightarrow x=7\)

=> Chọn A

a) \(\Rightarrow5x^2-15x=5x^2-x-10x+2-5\)

\(\Rightarrow5x^2-15x-5x^2+x+10x=2-5\)

\(\Rightarrow-4x=-3\)

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

Vậy \(x=\frac{3}{4}\)

b) \(\Rightarrow x^2-4x-5x+20-x^2+2x-x+2=7\)

\(\Rightarrow x^2-4x-5x-x^2+2x-x=7-20-2\)

\(\Rightarrow-8x=-15\)

\(\Rightarrow x=\frac{15}{8}\)

Vậy \(x=\frac{15}{8}\)

c) \(\Rightarrow3x^2-6x-4x+8=3x^2-27x-3\)

\(\Rightarrow3x^2-6x-4x-3x^2+27x=-3-8\)

\(\Rightarrow17x=-11\)

\(\Rightarrow x=\frac{-11}{17}\)

Vậy \(x=\frac{-11}{17}\)

Chúc bạn học tốt.