sos

A=(2x+1-2x+1)^2+xy

=xy+4

=2023+4

=2027

\(A=(2x+1-2x+1)^2+xy\)

\(=xy+4\)

\(=2023+4\)

\(=2027\)

a: \(N=\left(2x-3y\right)\left(2x+3y\right)=\left(2x\right)^2-\left(3y\right)^2\)

\(=4x^2-9y^2\)

Thay x=1/2 và y=1/3 vào N, ta được:

\(N=4\cdot\left(\dfrac{1}{2}\right)^2-9\left(\dfrac{1}{3}\right)^2\)

\(=4\cdot\dfrac{1}{4}-9\cdot\dfrac{1}{9}\)

=1-1

=0

b: \(N=\left(2x-y\right)\left(4x^2+2xy+y^2\right)\)

\(=\left(2x-y\right)\left[\left(2x\right)^2+2x\cdot y+y^2\right]\)

\(=\left(2x\right)^3-y^3=8x^3-y^3\)

Khi x=1 và y=3 thì \(N=8\cdot1^3-3^3=8-27=-19\)

a) \(A=4x^2-4x+1+9-4x^2=-4x+10\)

\(=-4.\dfrac{1}{4}+10=9\)

b) \(B=x^3+xy-x^3-8y^3=y\left(x-8y^2\right)\)

\(=\left(-2\right).\left(32-32\right)=0\)

a: Ta có: \(A=\left(2x-1\right)^2+\left(3-2x\right)\left(3+2x\right)\)

\(=4x^2-4x+1+9-4x^2\)

\(=-4x+10\)

\(=-4\cdot\dfrac{1}{4}+10=-1+10=9\)

\(a)\)

\(\left(2x+3\right)^2+\left(2x-3\right)^2-\left(2x+3\right)\left(4x-6\right)+xy\)

\(=\left(2x+3\right)^2-2\left(2x+3\right)\left(2x-3\right)+\left(2x-3\right)^2+xy\)

\(=\left(2x+3-2x+3\right)^2+xy\)

\(=6^2+2\left(-1\right)\)

\(=36-2\)

\(=34\)

\(b)\)

\(\left(x-2\right)^2-\left(x-1\right)\left(x+1\right)-x\left(1-x\right)\)

\(=x^2-4x+4-x^2+1-x+x^2\)

\(=x^2-5x+5\)

Thay \(x=-2\)vào ta có:

\(\left(-2\right)^2-5\left(-2\right)+5\)

\(=4+10+5\)

\(=19\)

ai giúp mik với

a: \(A=8x^3-1-7x^3-7=x^3-8\)

b: \(A=\left(-\dfrac{1}{2}\right)^3-8=\dfrac{-1}{8}-8=\dfrac{-65}{8}\)

\(A=x^3+8-x^3+2x=2x+8\)

\(A=x^3+8-x^3+2x=2x+8\\ A=2\cdot\dfrac{1}{2}+8=1+8=9\)

chịu

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

\(=-15x^2+10x+12x-8=-15x^2+22x-8\)

Thay x = -2 vào biểu thức ta có : \(-15\left(-2\right)^2+22\left(-2\right)-8\)

\(=-15.4-44-8=-112\)

b, \(B=\left(x-9\right)\left(2x+3\right)-2\left(x+7\right)\left(x-5\right)\)

\(=2x^2+3x-18x-27=2x^2-15x-27\)

Thay x = -1/2 vào biểu thức ta có : \(2\left(-\frac{1}{2}\right)^2-15\left(-\frac{1}{2}\right)-27\)

\(=2.\frac{1}{4}+\frac{15}{2}-27=\frac{11}{2}+\frac{15}{2}+27=40\)

Bài làm:

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

\(A=-15x^2+22x-8-2x^2+7x-6\)

\(A=-17x^2+29x-14\)

Thay x = -2 vào ta được:

\(A=-17.\left(-2\right)^2+29.\left(-2\right)-14\)

\(A=-68-58-14\)

\(A=-140\)

b) \(B=\left(x-9\right)\left(2x+3\right)-2\left(x+7\right)\left(x-5\right)\)

\(B=2x^2-15x-27-2\left(x^2+2x-35\right)\)

\(B=2x^2-15x-27-2x^2-4x+70\)

\(B=-19x+43\)

Thay x = -1/2 vào B ta được:

\(B=-19.\left(-\frac{1}{2}\right)+43=\frac{19}{2}+43=\frac{105}{2}\)

A = ( -5x + 4 )( 3x - 2 ) + ( -2x + 3 )( x - 2 )

A = -15x² + 22x - 8 - 2x² + 7x - 6

A = -17x² + 29x - 14

Thế x = -2 ta được :

A = -17(-2)² + 29(-2) - 14 = -68 - 58 - 14 = -140

b) B = ( x - 9 )( 2x + 3 ) - 2( x + 7 )( x - 5 )

B = 2x² - 15x - 27 - 2( x² + 2x - 35 )

B = 2x² - 15x - 27 - 2x² - 4x + 70

B = -19x + 43

Thế x = -1/2 ta được :

B = -19.(-1/2) + 43 = 19/2 + 43 = 105/2