Answer:
{-15, -5}
Step-by-step explanation:
The constant on the left needs to be the square of half the x-coefficient:
(20/2)^2 = 100
To get it to that value, we can add 18 to both sides of the equation:
x^2 +20x +100 = 25 . . . add 18 to both sides of the equation
(x +10)^2 = 25 . . . . . . . . write the left side as a square
x +10 = ±√25 = ±5 . . . . . take the square root
x = -10 ±5 = {-15, -5}
The solutions are x = -15 and x = -5.
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The attached graph shows the solutions to ...
x^2 +20x +82 -7 = 0 . . . . . the result of subtracting 7 from both sides
