Find the Focus y-4=3/8x^2

$y - 4 = \frac{3}{8} x^{2}$

Step 1

Rewrite the equation in vertex form.

Isolate $y$ to the left side of the equation.

Simplify $\frac{3}{8} x^{2}$ .

Rewrite.

$y - 4 = 0 + 0 + \frac{3}{8} x^{2}$

Simplify by adding zeros.

$y - 4 = \frac{3}{8} x^{2}$

Combine $\frac{3}{8}$ and $x^{2}$ .

$y - 4 = \frac{3 x^{2}}{8}$

Add $4$ to both sides of the equation.

$y = \frac{3 x^{2}}{8} + 4$

Complete the square for $\frac{3 x^{2}}{8} + 4$ .

Use the form $a x^{2} + b x + c$ , to find the values of $a$ , $b$ , and $c$ .

$a = \frac{3}{8}$

$b = 0$

$c = 4$

Consider the vertex form of a parabola.

$a {(x + d)}^{2} + e$

Find the value of $d$ using the formula $d = \frac{b}{2 a}$ .

Substitute the values of $a$ and $b$ into the formula $d = \frac{b}{2 a}$ .

$d = \frac{0}{2 (\frac{3}{8})}$

Simplify the right side.

Cancel the common factor of $0$ and $2$ .

Factor $2$ out of $0$ .

$d = \frac{2 (0)}{2 (\frac{3}{8})}$

Cancel the common factors.

Cancel the common factor.

$d = \frac{2 \cdot 0}{2 (\frac{3}{8})}$

Rewrite the expression.

$d = \frac{0}{\frac{3}{8}}$

Multiply the numerator by the reciprocal of the denominator.

$d = 0 (\frac{8}{3})$

Multiply $0$ by $\frac{8}{3}$ .

$d = 0$

Find the value of $e$ using the formula $e = c - \frac{b^{2}}{4 a}$ .

Substitute the values of $c$ , $b$ and $a$ into the formula $e = c - \frac{b^{2}}{4 a}$ .

$e = 4 - \frac{0^{2}}{4 (\frac{3}{8})}$

Simplify the right side.

Simplify each term.

Raising $0$ to any positive power yields $0$ .

$e = 4 - \frac{0}{4 (\frac{3}{8})}$

Combine $4$ and $\frac{3}{8}$ .

$e = 4 - \frac{0}{\frac{4 \cdot 3}{8}}$

Multiply $4$ by $3$ .

$e = 4 - \frac{0}{\frac{12}{8}}$

Cancel the common factor of $12$ and $8$ .

Factor $4$ out of $12$ .

$e = 4 - \frac{0}{\frac{4 (3)}{8}}$

Cancel the common factors.

Factor $4$ out of $8$ .

$e = 4 - \frac{0}{\frac{4 \cdot 3}{4 \cdot 2}}$

Cancel the common factor.

$e = 4 - \frac{0}{\frac{4 \cdot 3}{4 \cdot 2}}$

Rewrite the expression.

$e = 4 - \frac{0}{\frac{3}{2}}$

Multiply the numerator by the reciprocal of the denominator.

$e = 4 - (0 (\frac{2}{3}))$

Multiply $0$ by $\frac{2}{3}$ .

$e = 4 - 0$

Multiply $- 1$ by $0$ .

$e = 4 + 0$

Add $4$ and $0$ .

$e = 4$

Substitute the values of $a$ , $d$ , and $e$ into the vertex form $\frac{3}{8} {(x + 0)}^{2} + 4$ .

$\frac{3}{8} {(x + 0)}^{2} + 4$

Set $y$ equal to the new right side.

$y = \frac{3}{8} \cdot {(x + 0)}^{2} + 4$

Step 2

Use the vertex form, $y = a {(x - h)}^{2} + k$ , to determine the values of $a$ , $h$ , and $k$ .

$a = \frac{3}{8}$

$h = 0$

$k = 4$

Step 3

Find the vertex $(h, k)$ .

$(0, 4)$

Step 4

Find $p$ , the distance from the vertex to the focus.

Find the distance from the vertex to a focus of the parabola by using the following formula.

$\frac{1}{4 a}$

Substitute the value of $a$ into the formula.

$\frac{1}{4 \cdot \frac{3}{8}}$

Simplify.

Combine $4$ and $\frac{3}{8}$ .

$\frac{1}{\frac{4 \cdot 3}{8}}$

Reduce the expression by cancelling the common factors.

Multiply $4$ by $3$ .

$\frac{1}{\frac{12}{8}}$

Cancel the common factor of $12$ and $8$ .

Factor $4$ out of $12$ .

$\frac{1}{\frac{4 (3)}{8}}$

Cancel the common factors.

Factor $4$ out of $8$ .

$\frac{1}{\frac{4 \cdot 3}{4 \cdot 2}}$

Cancel the common factor.

$\frac{1}{\frac{4 \cdot 3}{4 \cdot 2}}$

Rewrite the expression.

$\frac{1}{\frac{3}{2}}$

Multiply the numerator by the reciprocal of the denominator.

$1 (\frac{2}{3})$

Multiply $\frac{2}{3}$ by $1$ .

$\frac{2}{3}$

Step 5

Find the focus.

The focus of a parabola can be found by adding $p$ to the y-coordinate $k$ if the parabola opens up or down.

$(h, k + p)$

Substitute the known values of $h$ , $p$ , and $k$ into the formula and simplify.

$(0, \frac{14}{3})$

Step 6

Find the Focus y-4=3/8x^2

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