a: \(\left(2x-3\right)^2=4x^2-12x+9\)

b: \(\left(x-3y\right)^2=x^2-6xy+9y^2\)

c: \(\left(2x+3y\right)\left(2x-3y\right)-\left(2x+y\right)^2\)

\(=4x^2-9y^2-4x^2-4xy-y^2=-8y^2-4xy\)

d: \(\left(x+3y^2\right)^2=x^2+6xy^2+9y^4\)

Chỉ cần dựa vào 7 hằng đẳng thức thôi nha bạn:

\(\left(2x-3\right)^2=2x^2-12x+9\)

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

\(\left(2x+3y\right)\left(2x-3y\right)-\left(2x+y\right)^2=2x^2-3y^2-2x^2+4xy-y^2=-3y^2+4xy-y^2\)\(\left(x+3y^2\right)^2=x^2+3y^22x+3y^4\)

Bạn dùng hằng đẳng thức ý

a. (A – B)²= A² – 2AB+ B²

^b. (A – B)²= A² – 2AB+ B²

c. (2x+3y)(2x-3y)-(2x+y)²

= 4x²-9y² -4x² - 4xy-y²

= -10y²-4x²

d. (A+B)² = A²+2AB+B²

a) (x + 3y) (2x²y - 6xy²)

= (x + 3y) + 2xy (x - 3y)

= 2xy [(x + 3y) (x - 3y)]

= 2xy (x² - 3y²)

b) (6x⁵y² - 9x⁴y³ + 15x³y⁴) : 3x³y²

= (6x⁵y² : 3x³y²) + (-9x⁴y³ : 3x³y²) + (15x³y⁴ : 3x³y²)

= [(6 : 3) (x⁵ : x³) (y² : y²)] + [(-9 : 3) (x⁴ : x³) (y³ : y²)] + [(15 : 3) (x³ : x³) (y⁴ : y²)]

= 2x² + (-3xy) + 5y²

= 2x² - 3xy + 5y²

#Học tốt!!!

a) \(\left(2x-3\right)^2=4x^2-12x+9\)

\(b.\left(x-3y\right)^2=x^2-6xy+9y^2\)

c) \(\left(2x+3y\right)\left(2x-3y\right)-\left(2x+y\right)^2\)

\(=\left(4x^2-9y^2\right)-\left(4x^2+4xy+y^2\right)\)

\(=-10y^2-4xy\)

\(=-2y\left(5y+2x\right)\)

d) \(\left(x+3y^2\right)^2\)

\(=x^2+6xy^2+9y^4\)

\(2x^3y-2xy^3-4xy^2-2xy\)

\(=2xy.\left(x^2-y^2-2y-1\right)\)

\(=2xy.[x^2-\left(y^2+2y+1\right)]\)

\(=2xy.[x^2-\left(y+1\right)^2]\)

\(=2xy.\left(x+y+1\right).\left(x-y-1\right)\)

Vậy chọn đáp án A

chọn A

Câu 4:B

Câu 7: A

Câu 8: B

Câu 11: C