Question 1

True or false?

the solution to the system of equations is (-1,7)

5x + y = -12
4x - y = 3

Question 2

$\text{Hey there!}$

$\checkmark\mathsf{The\ answer\ is\ \boxed{\mathsf{false}}}\checkmark$

$\text{Reason?}$

$\text{Here's\ the\ steps\ as\ to\ why\ it\ is\ \underline{false}}$

$\huge\text{\bf{Solving for y in the FIRST set} }$

$\mathsf{5x+y=-12}\\\mathsf{Add\ by\ -5x \ on\ your\ sides}\\\mathsf{5x+y+(-5x)=-12+(-5x)}\\\mathsf{If\ you\ solved\ that\ correctly\uparrow\ you\ should've\ came up\ with\downarrow}\\\mathsf{y=-5x-12}$

$\huge\text{\bf{Substitute the -5x - 12 for your y-value}}$
$\mathsf{4x-y=3}\\\mathsf{9x+12=3}\\\mathsf{Add\ by\ -12\ on\ your\ sides}\\\mathsf{9x+12+(-12)=3+(-12)}\\\mathsf{Cancel\ out\ 12 +(-12)\ because\ it\ gives\ us\ 0 }\\\mathsf{Keep: 3+(-12)\ because\ it\ gives\ us\ -9}\\\mathsf{New\ equation\ (for\ now)}\\\mathsf{9x=-9}\\\mathsf{Divide\ both\ sides\ by\ 9}\\\mathsf{(9x)/(9)=(-9)/(9)}\\\mathsf{Cancel\ out: (9x)/(9)\ because\ it\ equals\ 1}\\\mathsf{Keep: (-9)/(9)\ because\ gives\ you\ the\ value\ of\ x}$

$\huge\boxed{\text{\underline{x = -1}}}$

$\huge\text{\bf{Substitute your -1 as x}}$

$\mathsf{y=-5x-12}\\\mathsf{y= -5(-1)-12}\\\mathsf{-5(-1)=5}\\\mathsf{5-12=y}\\\mathsf{Simply\ that\ above\ \uparrow}\\\mathsf{If\ you\ solved\ correctly\ you\ have\ the\ value\ of\ y}$