10 points
Abby used the quadratic formula to find the zeros of the
function below. However, Abby made a mistake. What mistake
did Abby make? *
5x2 - 6x - 8 = 0
-
-b + b2 - 4ac
XE
2a
Step 1:
-(-6)(-6)2 - 4(5)(-8)
x=
2(5)
Step 2:
6 + V362 - 160
X =
10
Step 3:
6+1136
X =
= 3.97 AND X =
6-71136
10
10
-2.77
Step 1: She did not substitute her a, b and c values into the formula
correctly.
O Step 2: She did not simplify under the square root correctly.
O Step 3: She simplified her answers incorrectly.
She did not make a mistake and her answers are correct.
