a ) \(9x^2-6x+12\)
\(=\left(3x\right)^2-2.3x+1+11\)
\(=\left(3x-1\right)^2+11\ge11>0\forall x\)
\(\Rightarrowđpcm\)
b ) \(2x^2-2x+8\)
\(=2\left(x^2-x+4\right)\)
\(=2\left(x^2-x+\dfrac{1}{4}+\dfrac{15}{4}\right)\)
\(=2\left[\left(x-\dfrac{1}{2}\right)^2+\dfrac{15}{4}\right]\)
\(=2\left(x-\dfrac{1}{2}\right)^2+\dfrac{15}{2}\ge\dfrac{15}{2}>0\forall x\)
\(\Rightarrowđpcm\)
Tìm x:
a, 3.(2x-1).(3x-1)-(2x-3).(9x-1)-3=-3
b, (3x-1).(2x+7)-(x+1).(6x-5)=(x+2)-(x-5)
c, (6x-2)2+(5x-2)2-4.(3x-1).(5x-2)=0
d, (x+3)2-(x-4).(x+8)=1
e, 3.(x+2)2+(2x-1)2-7.(x+3).(x-3)=36
Tìm x, biết:
a) 3x(4x-3) - 2x(5-6x) = 0
b) 5(2x-3) + 4x(x-2) + 2x(3-2x) = 0
c) 3x(2-x) + 2x(x-1) = 5x(x+3)
d) 3x(x+1) - 5x(3-x) + 6(x2 + 2x + 3) = 0
Bài 1 : Tìm x, biết
a) 3x(x2 - 2) + x2(1-2x) - x2 = -12
b) 3x(2x +3) - (2x +5)(3x -2) = 8
c)3(3x -1)(2x+5) - 6(2x -1)(x+2) = -6
d) 3(2x -1)(3x - 1)- (2x -3)(9x -1) - 3 = -3
e) 4x(x-1)- 3(x2 -5)- x2 = (x-3)(x+4)
f) (3x-1)(2x+7)-(x+1)(6x-5)= (x+2)-(x-5)
Tìm x, biết
a) \(\left(3x+2\right)\left(2x+9\right)-\left(x+2\right)\left(6x+1\right)=\left(x+1\right)-\left(x-6\right)\)
b) \(3\left(2x-1\right)\left(3x-1\right)-\left(2x-3\right)\left(9x-1\right)=0\)
Tìm x , biết :
a) ( 3x -1 ) (2x+7) - ( x +1) (6x-5 ) = 16
b) ( 10x +9 )x - ( 5x -1 ) (2x+3 )= 8
c) ( 3x - 5 ) ( 7- 5x ) + ( 5x +2 )( 3x-2 ) -2 = 0
d) x(x + 1) ( x+6 ) - x3 = 5x
Tìm \(x\) , biết:
a) \(\left(x+2\right)\left(x+3\right)-\left(x-2\right)\left(x+5\right)=6\)
b) \(\left(3x+2\right)\left(2x+9\right)-\left(x+2\right)\left(6x+1\right)=\left(x+1\right)-\left(x-6\right)\)
c) \(3\left(2x-1\right)\left(3x-1\right)-\left(2x-3\right)\left(9x-1\right)=0\)
CÁC BẠN LÀM NHANH GIÚP MIK NHA!
Tìm x, biết:
a) (2x+2)(x-1)-(x+2)(2x+1)=0;
b)(3x+1)(2x-3)-6x(x+2)=16;
c)(12x-5)(4x-1)+(3x-7)(1-16x)=81
mn ơi giúp mik vs ạ :<
Tìm x
a) 3(2x-1)-5(x-3)+6(3x-4)=24
b) 6x²-(2x-3)(3x+2)-1=0
c) 4x²-12x=9
Bài 1: Thực hiện phép tính
a) (3x-1)(9x2+3x+1)-4x(x-5)
b) (7x+2)(3-4x)-(x+3)(x2-3x+9)
c) (4x+3)(4x-3)-(2-x)(4+2x+x2)
d) (3x-8)(-5x+6)-(4x+1)(3x-2)
e) (3x-6)4x-2x(3x+5)-4x2
f) (5x-6)(6x-5)-x(3x+10)
Bài 2 : Tính
a) x(x+3)-x2=6
b) 2x(x-5)+x(-2x-1)=6
c) x (x+5)-(x+1)(x-2)=7
d)(3x+4)(6x-3)-(2x+1)(9x-2)=10
