Question

Rút gọn:

A=(x^4 - 3x^2 + 9)(x^2 + 3) + (3 - x^2)^2

M= 5(x+2y)^2 - (3y + 2x)^2 + (4x - y)^2 + 3(x - 2y)(x + 2y)

E= (6x + 1)^2 + (6x - 1)^2 - 2(1 + 6x)(6x - 1)

C= (x^2 + 4)(x + 2)(x -2) - (x^2 - 3)^3

Answer 1

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

\(A=x^6-3x^4+9x^2+3x^4-9x^2+27+9-6x^2+x^4\)

\(A=x^6+x^4-6x^2+36\)

b, \(M=5\left(x+2y\right)^2-\left(3y+2x\right)^2+\left(4x-y\right)^2+3\left(x-2y\right)\left(x+2y\right)\)

\(M=5\left(x^2+4xy+4y^2\right)-\left(9y^2+12xy+4x^2\right)+\left(16x^2-8xy+y^2\right)+3\left(x^2-4y^2\right)\)

\(M=5x^2+20xy+20y^2-9y^2-12xy-4x^2+16x^2-8xy+y^2+3x^2-12y^2\)

\(M=20x^2\)

Các câu còn lại làm tương tự! Chúc bạn học tốt!!!

Answer 2

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

\(\Leftrightarrow\left(6x+1\right)^2-2\left(1+6x\right)\left(6x-1\right)+\left(6x-1\right)^2\)

\(\Leftrightarrow\left[\left(6x+1\right)-\left(6x-1\right)\right]^2\)

\(\Leftrightarrow\left(6x+1-6x+1\right)^2=2^2=4\)