Question

Which equation has this graph?
http://curriculum.kcdistancelearning.com/courses/ALG1x-HS-A06/b/Exams/8Quiz1/8Quiz1_q1.bmp
y = x2 - 6x + 5
y = -x2 - 6x + 5
y = -x2 - 6x - 5
y = x2 + 6x - 5

Answer 1

@vinnv226

Answer 2

well you know it's roots are 1 and 5

what does this tell you about the equation?

try to write it as a quadratic equation

Answer 3

Since the parabola opens upward, the x^2 term must have a positive coefficient, which eliminates the middle two options. From there, plug in x=0. You see from the graph that f(0)=5. See which of the two remaining equations gives you 5 when you plug in 0.

Answer 4

the first one = 5! @vinnv226

Answer 5

yes

Answer 6

replace x with 0 in the equation and you get
y = 0*0 - 6*0 + 5

0 times 0 is 0
-6*0 is 0
you get
y = 0+ 0 + 5
y = 5

Answer 7

of course the 2nd equation also gives +5, but rob already told you the -x2 would make the parabola open the wrong way....

Answer 8

one way to check is notice that on the graph, x=1 and y=0
so replace x with 1 in the equation:

the first choice
y = x2 - 6x + 5
with x=1 gives
y = 1*1 -6*1 +5 or
y = 1 - 6 +5 = -5+5 =0
so the first equation works. we could check the 2nd equation, but it will not work

Answer 9

okay thank you everyone im bout to post another if you don't mind helping me i would b very happy:)