Question

please help!!!

Answer 1

put it in standard form first

ax^2 + bx + c = 0

c is negative 5, not plus 5

Answer 2

okay

Answer 3

so the mistake starts from the first step?

Answer 4

hint:
your equation is:
\[{x^2} + 4x - 5 = 0\]

Answer 5

i got that part:)

Answer 6

a=1,b=4,c=-5

Answer 7

yes!
the right answer is:
\[\begin{gathered}
x = \frac{{ - 4 \pm \sqrt {{{\left( { - 4} \right)}^2} - 4 \times 1 \times \left( { - 5} \right)} }}{{2 \times 1}} = \hfill \\
\hfill \\
= \frac{{ - 4 \pm \sqrt {16 + 20} }}{2} = \frac{{ - 4 \pm 6}}{2} = ...? \hfill \\
\end{gathered} \]

Answer 8

1 and -5

Answer 9

that's right!

Answer 10

but i need to explain where the student went wrong

Answer 11

does she go wrong since the beginning because she put 5 instead of -5?

Answer 12

the student was wrong, since the coefficient c is -5 not +5

Answer 13

namely:
\[\Large c = - 5\]
before applying the formula:
\[\Large x = \frac{{ - b \pm \sqrt {{b^2} - 4 \times a \times c} }}{{2 \times a}}\]
we have to write our quadratic equation, in this form:
\[\Large a{x^2} + bx + c = 0\]

Answer 14

okay, thanks so much!! :)

Answer 15

thanks!