Hi there!
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In order to set each equation equal to each other, we must have them both equal the same variable.
Rearrange the top equation to make it equal to y:
x - y = -4
Add 4 to both sides and add y to both sides:
x + 4 = y
Now, we can set both equations equal to each other:
x + 4 = 5(x + 1)² - 3
Begin solving by expanding the square binomial:
x + 4 = 5(x² + 2x + 1) - 3
Simplify:
x + 4 = 5x² + 10x + 5 - 3
x + 4 = 5x² + 10x + 2
Bring all terms to one side:
0 = 5x² + 9x - 2
Factor:
0 = (5x - 1)(x + 2)
Set the other factor equal to 0:
5x - 1 = 0
5x = 1
x = 1/5
Plug in this value of x into an original equation:
1/5 - y = -4
1/5 + 4 = y
1/5 + 20/5 = y
y = 21/5