Question

[IzanamiAiko123]

Rút gọn biểu thức

a) A= (2x-5)²-4x(x-6)

b) B= (7x-3y)²-(7x-3y)(7x+3y)

c) C= (3-2x)²+(3+2x)²

d) D= (x-y+z)²+(z-y)²+2(x-y+z)(y-z)

MÌNH CẦN GẤP LẮM, MẤY BẠN GIÚP MÌNH NHA. HỨA SẼ TICK CHO BẠN NÀO LÀM NHANH NHẤT Ạ!!

Answer 1

[Nguyễn Linh Chi]

\(A=\left(2x\right)^2-2.2x.5+5^2-4x.x+4x.6\)

\(=4x^2-20x+25-4x^2+24x=4x+25\)

\(B=\left(7x-3y\right)^2-\left(7x-3y\right)\left(7x+3y\right)\)

\(=\left(7x-3y\right)\left(7x-3y-7x-3y\right)\)

\(=\left(7x-3y\right)\left(-6y\right)=18y^2-42xy\)

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

\(=9-2.3.2x+4x^2+9+2.3.2x+4x^2\)

\(=18+8x^2\)

\(D=\left(x-y+z\right)^2+\left(z-y\right)^2+2\left(x-y+x\right)\left(y-z\right)\)

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