Question

F(x) = 2x2 – 4x – 3

0 = 2x2 – 4x – 3

3 = 2(x2 – 2x)

3 + 1 = 2(x2 – 2x + 1)

4 = 2(x – 1)2

2 = (x – 1)2

± = x – 1

1 ± = x

Mica is solving for the zeros of a quadratic function by completing the square. Her work is shown. What error did Mica make?




ANSWER CHOICES
Mica should have set each x = 0 instead of f(x).
Mica should have added 2 to 3 instead of 1.
Mica should have multiplied both sides by 2 instead of dividing.
Mica should have subtracted 1 from both sides instead of adding.

Answer 1

mica should have added 2 to 3 instead of 1

Answer 2

Mica should have added 2 to 3 instead of 1.

Explanation:

f(x) = 2x^2 – 4x – 3

0 = 2x^2 – 4x – 3

Mica added 3 on boths sides and factored out 2

3 = 2(x^2 – 2x)

We have 2 outside the parenthesis , so we multiply 1 with 2 and add it one left side

3 + 1 = 2(x^2 – 2x + 1) Error in this step

The above step becomes 3 + 2 = 2(x^2 – 2x + 1)

Mica should have added 2 to 3 instead of 1.