\(a.\left(10x+9\right)x-\left(5x-1\right)\left(2x+3\right)=8.\)
\(\Leftrightarrow10x^2+9x-\left(10x^2+15x-2x-3\right)=8\)
\(\Leftrightarrow10x^2+9x-10x^2-13x+3=8\)
\(\Leftrightarrow-4x+3=8\)
\(\Leftrightarrow-4x=5\)
\(\Leftrightarrow x=-\frac{5}{4}\)
\(b.\left(3x-5\right)\left(7-5x\right)+\left(5x-2\right)\left(3x-2\right)-2=0\)
\(\Leftrightarrow21x-15x^2-35+25x+15x^2-10x+6x-4-2=0\)
\(\Leftrightarrow42x-41=0\)
\(\Leftrightarrow42x=41\)
\(\Leftrightarrow x=\frac{41}{42}\)
a, (10x+9) x -(5x-1) (2x +3 )=8
= 10x2+ 9x-(10x2 +15x -2x -3) =8
= 10x2+9x - 10x2 -13x +3 =8
= - 4 x +3 =8
= - 4 x =5
suy ra x= -5/4
b, (3x -5)(7-5x)+(5x+2) (3x -2) -2 =0
= 21x -15x2 - 35 +25x + 15x2 -10x +6x -4 -2 =0
=42x -41 =0
suy ra x= 41/42
