<PRE><B>Question 408284</B>
solve the system by substitution.
   x + y =-7
   x = y + 19
Use the 2nd equation for substitution in the 1st equation
In the 1st equation replace x with (y+19)
(y+19) + y = -7
2y = -7 - 19
2y = -26
y = {{{-26/2}}}
y = -13
Find x using the 2nd equation, replace y with -13
x = -13 + 19
x = +6
check solutions, substitute for x and y in the 1st equation
6 - 13 = -7
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also 2. x^2=5 
Find the square root of both sides
x = +/-{{{sqrt(5)}}}</PRE>