SOLUTION: When asked to solve x^2 + 4x = 5 by using the quadratic formula, a student did the
following:
x = -4±(√4^2-4·1·5)/2·1 = -4±(√16-20)/2 = -4±(√-4)/2 = -2±i
W
Algebra.Com
Question 381590: When asked to solve x^2 + 4x = 5 by using the quadratic formula, a student did the
following:
x = -4±(√4^2-4·1·5)/2·1 = -4±(√16-20)/2 = -4±(√-4)/2 = -2±i
What did the student do wrong?
Found 2 solutions by Fombitz, rapaljer:
Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
Didn't first bring the 5 over to the other side.
She could have then factored instead of using the quadratic formula to get,
with and as solutions.
.
.
.
Instead she used instead of in the quadratic formula and got the wrong answer.
Answer by rapaljer(4671) (Show Source): You can put this solution on YOUR website!
First, you have to set the equation EQUAL to ZERO.
x^2 + 4x - 5 = 0
a=1, b=4, and c=-5.
In the square root, the student should have had
Dr. Rapalje
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