What are the vertex and x-intercepts of the graph of y= x2 - 6x - 7?Select
one answer for the vertex and one for the x-intercepts.
A. x-intercepts: (1,0), (7,0)
B. Vertex: (3,-16)
C.Vertex: (-3,20)
D. Vertex: (3, 20)
E. x-intercepts: (-1,0). (7.0)
F. x-intercepts: (1.0), (-7,0)

Respuesta :

The answer is B and E

The vertex and [tex]x-[/tex]intercepts of the graph of [tex]y= x^2 - 6x - 7[/tex] will be  [tex](3,-16)[/tex] and [tex](7,-1)[/tex], respectively.

What are vertex and  [tex]x-[/tex]intercepts of the graph?

A vertex in a quadratic equation is the minimum or maximum point of the equation and  an [tex]x-[/tex]intercept of a graph is the point at which the graph intersects the [tex]x-[/tex]axis.

Vertex form, [tex]y=a(x-h)^2+k[/tex]

We have,

[tex]y= x^2 - 6x - 7[/tex]

Now,

Find the [tex]x-[/tex]intercept  and to find [tex]x-[/tex]intercept put [tex]y=0[/tex] ;

i.e. [tex]y= x^2 - 6x - 7[/tex]

[tex]0= x^2 - 6x - 7[/tex]

[tex]x^2 - 6x - 7=0[/tex]

Now using Mid-term split method find value of [tex]x[/tex];

[tex]x^2 - 7x+1x - 7=0[/tex]

[tex]x(x - 7)+1(x - 7)=0[/tex]

[tex](x - 7)(x +1)=0[/tex]

[tex](x - 7)=0[/tex]⇒[tex]x=7[/tex]

[tex](x +1)=0[/tex]⇒[tex]x=-1[/tex]

So, these are the [tex]x-[/tex]intercept [tex](7,-1)[/tex] of the expression.

Now find the vertex using the above given formula;

[tex]y=a(x-h)^2+k[/tex]

Rewrite in vertex form

[tex]y= x^2 - 6x - 7[/tex]

Add and subtract [tex](-3)^2[/tex] in given expression;

[tex]y= x^2 - 6x + (-3)^2 -7 - (-3)^2[/tex]

[tex]y = x^2 - 6x + 9 -7 - 9[/tex]

[tex]y = x^2 - 6x + 9 -16[/tex]

Now convert quadratic part of equation in [tex](a-b)^2[/tex];

[tex]y = (x-3)^2-16[/tex]

Now compare it with [tex]y=a(x-h)^2+k[/tex]

We get,  [tex]h=3,\ k=-16[/tex]

So, these are the vertex [tex](3,-16)[/tex] of expression.

Hence, we can say that the vertex and [tex]x-[/tex]intercepts of the graph of [tex]y= x^2 - 6x - 7[/tex] will be  [tex](3,-16)[/tex] and [tex](7,-1)[/tex], respectively.

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