Question

Which graph represents the function y = –2x² – 5?
https://www.connexus.com/content/chrome/online/default.aspx?idSection=164909&idLesson=138060&idWebuser=532739

Answer 1

we can not see that but let's look at the question
you have
y = –2x² – 5

you can find the graph easily
you know it has a negative coefficient of x² so it must be a hill shape

next if you look at the equation, you know that it crosses the y axis at -5, because
y=mx+c is the standard equation of a line where c is the y intercept

so you know that it is a hill shape, that crosses the y axis at -5

now if you let the equation equal 0 we can see when it hits the x axis
-2x²-5=0
-2x²=5
x²=-5/2
you can not square root a negative so this means it has no real roots, therefore it doesn't touch the x axis

so now you know
it never touches the x axis
it crosses the y axis at -5
and it is hill shaped



that is what I mean by h ill shape

Answer 2

Thanks a lot :)

Answer 3

give me a meddle please :)

Answer 4

Hi