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Find linear equation
X+y=7
X-y=9

Sagot :

Jeremiaidn
x + y = 7
x - y = 9

x - 7 = -y
(x / -1) -7/-1 = -y/-1
-x + 7 = y

x - y = 9
x -(-x + 7) = 9
x + x - 7 = 9
2x - 7 = 9
2x = 9 + 7
2x = 16
2x/2 = 16/2
x = 8
x + y = 7
8 + y =7
8 + y -8 = 7-8
y=-1
Check:
x + y = 7
8 + -1 = 7,
7 = 7, Correct

x-y = 9
8 - (-1) = 9
8 +1 = 9
9 = 9, Correct
Therefore, x = 8 and y=-1
Dominiidn
[tex]x+y=7----Equation\ 1 \\ x-y=9----Equation\ 2 \\ \\ Give\ the\ value\ of\ y\ by\ using\ slope-intercept\ form; \\ \\ y=mx+b \\ x-y=9\to\ x-9=-y\to\ \frac{x}{-1}- \frac{9}{-1}= \frac{-y}{-1}\to \boxed{\boxed{y=-x+9}} \\ \\ x-(-x+9)=7 \\ \\ x+x-9=7 \\ \\ 2x=7+9 \\ \\ \frac{2x}{2}=\frac{16}{2} \\ \\ \boxed{x=8} \\ \\ Solving\ for\ y\ where\ x\to8; \\ \\ x-y=9 \\ \\ 8-y=9 \\ \\ -y=9-8 \\ \\ \frac{-y}{-1}=\frac{1}{-1} \\ \\ \boxed{y=-1} [/tex]

[tex]Checking; \\ \\ By\ using\ equation\ 1\ where\ x\to8\ and\ y=-1 \\ \\ Equation\ 1; \\ x+y=7 \\ \\ 8+(-1)=7 \\ \\ 8-1=7 \\ \\ 7=7\ \underline{TRUE} \\ \\ Equation\ 2; \\ x-y=9 \\ \\ 8-(-1)=9 \\ \\ 8+1=9 \\ \\ 9=9\ \underline{TRUE} \\ \\ Thus,x\ and\ y\ are\ 8\ and\ -1\ respectively \\ \\Hope\ it\ Helps:) \\ Domini[/tex]