作业帮求正确答案,还要有式子!
来源：学生作业帮助网 编辑：作业帮 时间：2024/11/27 06:24:37
xQN@o(ۏŦY4GAtl$$(X!D$H .8ajΝslrz:3 {v69^L|hm r¸8uS;wH&|4* yQѰ ^ ӼP|NUC $1&" B*,BiIJJ2|F
A3)",Rd UHJ %RL#(`GL!J$8<%Y@+m֍lcKq+xujmz;u<.r wg O״wmRӞ×y:k1J>X(
&Xͧ b=п
求正确答案,还要有式子!
求正确答案,还要有式子!
求正确答案,还要有式子!
x^2+xy+y^2
=x^2+2xy+y^2-xy
=(x+y)^2-xy x=√2+1 y=√2-1 x+y=2√2 xy=1
=(2√2)^2-1
=8-7
=7
3(a+1)^2-(a+1)(2a-1)
=3(a^2+2a+1)-(2a^2+a-1)
=3a^2+6a+3-2a^2-a+1
=a^2+5a+4
=(a+1)(a+4) a=1
=2*5
=10
x-y=2，xy=1
x²+xy+y²=（x-y）²+3xy=4+3=7