Maths-
General
Easy
Question
x(x + 2) = 8
Which of the following lists all solutions to the quadratic equation above?
- 8 and 6
- 4 and -2
- -4 and 2
The correct answer is: -4 and 2
HINT: Expand the given equation and then solve the quadratic equation.
Given equation is x(x + 2) = 8
By using distributive property, we get the equation to be x2 + 2x = 8…(i)
Subtract 8 from both sides of (i)
we get x2 + 2x - 8 = 0, which is the required quadratic equation.
We can solve the quadratic equation using quadratic formula 
Here, a = 1, b = 2, c = -8
By substituting these values in the quadratic formula,
We get 
After simplification, we get x = 2 and -4
So, the roots are 2 and -4.
Hence option C is the correct answer.
Note: We can also solve this equation by substituting the values provided in the options. In the end, we will get the
solutions as 2 and -4.
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