Question

Giải hpt

x + y = 36

20.(y + 20) = x + 20

 

 

Answer 1

Lời giải:

$x+y=36\Leftrightarrow y=36-x$

Thay vào PT(2):

$20(36-x+20)=x+20$

$\Leftrightarrow 20(56-x)=x+20$

$\Leftrightarrow 1120-20x=x+20$

$\Leftrightarrow 1100=21x$

$\Leftrightarrow x=1100:21=\frac{1100}{21}$

$y=36-x=36-\frac{1100}{21}=\frac{-344}{21}$