Question

Rezolvați sistemele de ecuații puncte puncte A minus 7x plus 18 x y egal 47 minus 3x plus 11 egal 30 b 3x minus 5y egal 24 x plus 15 x y egal 7 ​

Answer 1

Răspuns:

a)$\left. \begin{array} { l } { - 7 x + 18 y = 47 } \\ { - 3 x + 11 y = 30 } \end{array} \right.$

$-7x+18y=47,-3x+11y=30$

$-7x+18y=47$

$-7x=-18y+47$

$x=-\frac{1}{7}\left(-18y+47\right)$

$x=\frac{18}{7}y-\frac{47}{7}$

$-3\left(\frac{18}{7}y-\frac{47}{7}\right)+11y=30$

$-\frac{54}{7}y+\frac{141}{7}+11y=30$

$\frac{23}{7}y+\frac{141}{7}=30$

$\frac{23}{7}y=\frac{69}{7}$

$y=3$

$x=\frac{18}{7}\times 3-\frac{47}{7}$

$x=\frac{54-47}{7}$

$x=1$

$x=1,y=3$

b) x = 1

y = 1/5 =》 y = 0.2