What is the vertex form of y=2x^2+7x+3 ?

1 Answer
Aug 12, 2017

The vertex form is y=2(x+7/4)^2-25/8.

Explanation:

y=2x^2+7x+3 is a quadratic equation in standard form:

y=ax^2+bx+c, where a=2, b=7, and c=3.

The vertex form is y=a(x-h)^2+k, where (h,k) is the vertex.

In order to determine h from the standard form, use this formula:

h=x=(-b)/(2a)

h=x=(-7)/(2*2)

h=x=-7/4

To determine k, substitute the value of h for x and solve. f(h)=y=k

Substitute -7/4 for x and solve.

k=2(-7/4)^2+7(-7/4)+3

k=2(49/16)-49/4+3

k=98/16-49/4+3

Divide 98/16 by color(teal)(2/2

k=(98-:color(teal)(2))/(16-:color(teal)(2))-49/4+3

Simplify.

k=49/8-49/4+3

The least common denominator is 8. Multiply 49/4 and 3 by equivalent fractions to give them a denominator of 8.

k=49/8-49/4xxcolor(red)(2/2)+3xxcolor(blue)(8/8

k=49/8-98/8+24/8

k=-25/8

The vertex form of the quadratic equation is:

y=2(x+7/4)^2-25/8

graph{y=2x^2+7x+3 [-10, 10, -5, 5]}