Ask your own question, for FREE!
Mathematics 18 Online
OpenStudy (hothotleg):

AN/MEDAL/TESTIMONY Quadratic Equations

OpenStudy (hothotleg):

What is the equation of the axis of symmetry if the x-intercepts are (-4,0) and (10,0)? Explanation please! Thank you! ^u^

satellite73 (satellite73):

what is half way between \(-4\) and \(10\)?

satellite73 (satellite73):

which is another way of asking "what is the average of -4 and 10?"

OpenStudy (hothotleg):

Half way between -4 and 10? I don't understand, but I would think it's somewhere around the number 5?

satellite73 (satellite73):

somewhere around that yes, but not there

satellite73 (satellite73):

same as saying what is \[\frac{-4+10}{2}\]

OpenStudy (shastri007):

Here it is x = -3

OpenStudy (shastri007):

This would be the answer the teacher would be looking for!

OpenStudy (hothotleg):

Oh! Well thank you, but I need an explanation too!

satellite73 (satellite73):

careful here

satellite73 (satellite73):

just because the roots are \(10\) and \(-4\) dots not mean the quadratic is \[(x-10)(x+4)\]

satellite73 (satellite73):

but it does mean the axis of symmetry is half way between those two roots since the average of \(10\) and \(-4\) is \[\frac{10-4}{2}=3\] that means the axis of symmetry is \(x=3\)

OpenStudy (shastri007):

Okay Since we know the x-intercepts as -4 and 10 We can replug it back into the factor form, x=-4 this becomes (x+4) and x=10 becomes (x-10) we take (x+4) multiply by (x-10) we now get the quadratic equation Take the quadratic equation into the form ax^2 + bx +c Use the formula for axis of symmetry as x = b/2a

OpenStudy (shastri007):

@satellite73 We only are certain its a quadratic when we multiply them out

satellite73 (satellite73):

it might be \[(x+4)(x-10)\] but it also might be \[2\pi(x+4)(x-10)\]

satellite73 (satellite73):

and we are certain it is a quadratic because they say it has to roots and an axis of symmetry

satellite73 (satellite73):

*two roots

OpenStudy (shastri007):

Yeup

OpenStudy (hothotleg):

Oh! Thank you!

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!