Câu hỏi của Nèk Zyy'z

Question

Bài 7: Tính

a) $(3x^2-2xy+y^2)+(x^2-xy+2y^2)-(4x^2-y^2)$

b) $(x^2-y^2+2xy)-(x^2+xy+2y^2)+(4xy-1)$

✿✿❑ĐạT̐®ŋɢย❐✿✿ · Accepted Answer

a) $\left(3x^2-2xy+y^2\right)+\left(x^2-xy+2y^2\right)-\left(4x^2-y^2\right)$

$=3x^2-2xy+y^2+x^2-xy+2y^2-4x^2+y^2$

$=4y^2-3xy$

b) $\left(x^2-y^2+2xy\right)-\left(x^2+xy+2y^2\right)+\left(4xy-1\right)$

$=x^2-y^2+2xy-x^2-xy-2y^2+4xy-1$

$=-3y^2+5xy-1$Câu trả lời: a) $\left(3x^2-2xy+y^2\right)+\left(x^2-xy+2y^2\right)-\left(4x^2-y^2\right)$

$=3x^2-2xy+y^2+x^2-xy+2y^2-4x^2+y^2$

$=4y^2-3xy$

b) $\left(x^2-y^2+2xy\right)-\left(x^2+xy+2y^2\right)+\left(4xy-1\right)$

$=x^2-y^2+2xy-x^2-xy-2y^2+4xy-1$

$=-3y^2+5xy-1$

Nguyễn Thanh Hằng · Answer

a/ $\left(3x^2-2xy+y^2\right)+\left(x^2-xy+2y^2\right)-\left(4x^2-y^2\right)$

$=3x^2-2xy+y^2+x^2-xy+2y^2-4x^2+y^2$

$=-3xy+4y^2$

b/ $\left(x^2-y^2+2xy\right)-\left(x^2+xy+2y^2\right)+\left(4xy-1\right)$

$=x^2-y^2+2xy-x^2-xy-2y^2+4xy-1$

$=-3y^2+5xy-1$Câu trả lời: a/ $\left(3x^2-2xy+y^2\right)+\left(x^2-xy+2y^2\right)-\left(4x^2-y^2\right)$

$=3x^2-2xy+y^2+x^2-xy+2y^2-4x^2+y^2$

$=-3xy+4y^2$

b/ $\left(x^2-y^2+2xy\right)-\left(x^2+xy+2y^2\right)+\left(4xy-1\right)$

$=x^2-y^2+2xy-x^2-xy-2y^2+4xy-1$

$=-3y^2+5xy-1$

Chương IV : Biểu thức đại số