markdown左对齐

在需要左对齐的部分前后加上一些东西，每行最前面加上&即可。

若要等式对齐，则将&放在等号前面。要按哪个字符对齐，就将&放在哪个字符后面。

$$
begin{aligned}
& a=1\
& a+b=2\
& a+b+c=3
end{aligned}
$$

a = 1 a + b = 2 a + b + c = 3 begin{aligned} & a=1\ & a+b=2\ & a+b+c=3 end{aligned} ​a=1a+b=2a+b+c=3​

等式对齐

$$
begin{aligned}
x^2 + 6x + 8 &= (x+3)^2-9+8 \
 &= (x+3)^2-1 \
 &= (x+4)(x+2) 
end{aligned}
$$

( x + 1 ) 2 = ( x + 1 ) ⋅ ( x + 1 ) = x ( x + 1 ) + ( x + 1 ) = x 2 + x + x + 1 = x 2 + 2 x + 1 begin{aligned} (x+1)^2 &= (x+1)cdot (x+1) \ &= x(x+1)+(x+1) \ &= x^2+x+x+1 \ &= x^2+2x+1 end{aligned} (x+1)2​=(x+1)⋅(x+1)=x(x+1)+(x+1)=x2+x+x+1=x2+2x+1​

按某个字符对齐

$$
begin{aligned}
I  &like  running.\
He  &like  swimming.\
She  &like  dancing.
end{aligned}
$$

I   l i k e   r u n n i n g . H e   l i k e   s w i m m i n g . S h e   l i k e   d a n c i n g . begin{aligned} I &like running.\ He &like swimming.\ She &like dancing. end{aligned} I He She ​like running.like swimming.like dancing.​