SOLUTION: f(X)=x2-8X-6 thats x squared what is the vertex what is the x intercept what is the axis symmetry what is the graph look like does it open up or down

Algebra ->  Rational-functions -> SOLUTION: f(X)=x2-8X-6 thats x squared what is the vertex what is the x intercept what is the axis symmetry what is the graph look like does it open up or down       Log On


   



Question 799088: f(X)=x2-8X-6
thats x squared
what is the vertex
what is the x intercept
what is the axis symmetry
what is the graph look like
does it open up or down

Found 2 solutions by solver91311, MathLover1:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


First thing you must learn: X is NOT the same thing as x. The only way we have to communicate is in writing, so make SURE you don't type something incorrectly.

Second, ^ (Shift-6) means "raise to the power", so x^2 means



The -coordinate of the vertex is at

The -coordinate of the vertex is

The -intercepts, if they exist, are at and where



and



The equation of the axis of symmetry is , which is to say the vertical line through the vertex.

It looks exactly like a parabola.

It opens upward if , downward otherwise.

John

Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it
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Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
The standard form of a parabola's equation is generally expressed:
y+=+ax%5E2+%2B+bx+%2B+c
The role of 'a'
if a%3E+0, the parabola opens upwards
if a%3C+0, it opens downwards
The axis of symmetry is the line x+=+-b%2F2a+
given:
f%28x%29=x%5E2-8x-6...=>f%28x%29=y, a=1,b=-8, and c=-6
so, since a=1 =>a%3E+0, the parabola opens upwards
The axis of symmetry is the line x+=+-b%2F2a+
x+=+-%28-8%29%2F2%2A1+
x+=8%2F2+
x+=4+
The vertex form of a parabola's equation is generally expressed as :
y=+a%28x-h%29%5E2%2Bk
(h,k) is the vertex
f%28x%29=%28x%5E2-8x%2B_%29-6..complete square
f%28x%29=%28x%5E2-8x%2B4%5E2%29-6
f%28x%29=%28x-4%29%5E2-16-6

f%28x%29=%28x-4%29%5E2-22....=> h=4 and k=-22
so, (4,-22) is the vertex

the x intercept: set f%28x%29=0 and solve for x
0=x%5E2-8x-6.........use quadratic formula
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-%28-8%29+%2B-+sqrt%28+%28-8%29%5E2-4%2A1%2A%28-6%29+%29%29%2F%282%2A1%29+
x+=+%288+%2B-+sqrt%28+64%2B24+%29%29%2F2+
x+=+%288+%2B-+sqrt%28+88%29%29%2F2+
x+=+%288+%2B-+9.38%29%2F2+
solutions:
x+=+%288+%2B+9.38%29%2F2+
x+=+17.38%2F2+
x+=+8.69+
or
x+=+%288+-+9.38%29%2F2+
x+=+-1.38%2F2+
x+=+-0.69+
so, the x intercepts are (8.69,0) and (-0.69,0)