giai phuong trinh
a, 3(x – 1) ( 2x – 1) = 5(x + 8) (x – 1)
b, 9x^2 – 1 = ( 3x + 1) (4x+1)
c, (x + 7) (3x – 1) = 49 – x^2
d, (2x +1)^2 = ( x – 1)^2
e, ( x^3 – 5x^2 +6x = 0
g, 2x^3 + 3x^2 = 32x – 48
giup minhh
giai phuong trinh
a, 3(x – 1) ( 2x – 1) = 5(x + 8) (x – 1)
b, 9x^2 – 1 = ( 3x + 1) (4x+1)
c, (x + 7) (3x – 1) = 49 – x^2
d, (2x +1)^2 = ( x – 1)^2
e, ( x^3 – 5x^2 +6x = 0
g, 2x^3 + 3x^2 = 32x – 48
giup minhh
Đáp án:
a) 3(x – 1) ( 2x – 1) = 5(x + 8) (x – 1)
↔ 3(x – 1) ( 2x – 1) – 5(x + 8) (x – 1) = 0
↔ ( x – 1 )[ 3( 2x – 1 ) – 5( x + 8 ) ] = 0
↔ ( x – 1 ) ( 6x – 3 – 5x – 40 ) = 0
↔ ( x – 1 )( x – 43 ) = 0
↔$\left \{ {{x-1=0} \atop {x-43=0}} \right.$
↔ $\left \{ {{x=1} \atop {x=43}} \right.$
b) 9x² – 1 = ( 3x + 1) (4x+1)
↔ ( 3x + 1 )( 3x – 1 ) – ( 3x + 1) (4x+1) = 0
↔ ( 3x + 1 )( 3x – 1 – 4x – 1 ) = 0
↔ ( 3x + 1 )( -2 – x ) = 0
↔ $\left \{ {{3x+ 1=0} \atop {-2-x=0}} \right.$
↔$\left \{ {{x=\frac{-1}{3}} \atop {x=-2}} \right.$
c) (x + 7) (3x – 1) = 49 – x^2
↔ (x + 7) (3x – 1) – ( 7 – x )( x + 7 ) = 0
↔ ( x + 7 )( 3x – 1 – 7 + x ) = 0
↔ ( x+ 7 )( 4x – 8 ) = 0
↔ $\left \{ {{x + 7=0} \atop {4x+8=0}} \right.$
↔ $\left \{ {{x=-7} \atop {x=2}} \right.$
d) ( 2x + 1)² = ( x – 1)²
↔ ( 2x + 1 + x – 1 )( 2x + 1 -x + 1 ) = 0
↔ 3x( x+ 2 ) = 0
↔$\left \{ {{3x=0} \atop {x+2=0}} \right.$
↔$\left \{ {{x=0} \atop {x=-2}} \right.$
e) x³ – 5x² + 6x = 0
↔ x( x² – 5x + 6 ) = 0
↔ x( x² – 2x -3x + 6 ) = 0
↔ x[ x( x – 2) – 3( x – 2 ) ] = 0
↔ x( x – 2 )( x – 3 ) = 0
↔ x = 0
$\left \{ {{x-2=0} \atop {x-3=0}} \right.$
↔x = 0
$\left \{ {{x=2} \atop {x=3}} \right.$
g) 2x³ + 3x² = 32x – 48
Đề câu g sai =)))
Xem lại dấu ạ