Question

Using the quadratic formula to solve x2 = 5 - X, what are the values of X?

-1 √21
2
-13 19
51-421
1119
2
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Answer 1

The answer is

`x = ( - 1 + √(21) )/(2) \: \: \: or \: \: \: x = ( - 1 - √(21) )/(2)`

Explanation:

x² + x - 5 = 0

Using the quadratic formula

That's

`x = \frac{ - b\pm \sqrt{ {b}^(2) - 4ac } }{2a}`

From the question

a = 1 , b = 1 , c = - 5

Substitute the values into the above formula and solve

We have

`x = \frac{ - 1\pm \sqrt{ {1}^(2) - 4(1)( - 5) } }{2(1)} \\ x = ( - 1\pm √(1 + 20 ) )/(2) \\ x = ( - 1\pm √(21) )/(2)`

We have the final answer as

`x = ( - 1 + √(21) )/(2) \: \: \: or \: \: \: x = ( - 1 - √(21) )/(2)`

Hope this helps you