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Write the parametric equations in rectangular form.

[tex]\[
\begin{array}{l}
y=2t^2+6 \\
x=5t-8
\end{array}
\][/tex]

A. [tex]\( y=\frac{2}{25}x^2+\frac{32}{25}x+\frac{278}{25} \)[/tex]

B. [tex]\( y=\frac{2}{25}x^2-\frac{32}{25}x+\frac{278}{25} \)[/tex]

C. [tex]\( y=\frac{2}{25}x^2+\frac{32}{25}x+\frac{22}{25} \)[/tex]

D. [tex]\( y=-\frac{2}{25}x^2+\frac{32}{25}x+\frac{278}{25} \)[/tex]


Sagot :

To write the parametric equations [tex]\( y = 2t^2 + 6 \)[/tex] and [tex]\( x = 5t - 8 \)[/tex] in rectangular form, we need to eliminate the parameter [tex]\( t \)[/tex]. Let's do this step by step.

1. Solve for [tex]\( t \)[/tex] in terms of [tex]\( x \)[/tex]:

Given [tex]\( x = 5t - 8 \)[/tex], we solve for [tex]\( t \)[/tex]:
[tex]\[ x + 8 = 5t \][/tex]
[tex]\[ t = \frac{x + 8}{5} \][/tex]

2. Substitute [tex]\( t \)[/tex] into the equation for [tex]\( y \)[/tex]:

Substitute [tex]\( t = \frac{x + 8}{5} \)[/tex] into [tex]\( y = 2t^2 + 6 \)[/tex]:
[tex]\[ y = 2 \left( \frac{x + 8}{5} \right)^2 + 6 \][/tex]

3. Simplify the expression:

First, square [tex]\( \frac{x + 8}{5} \)[/tex]:
[tex]\[ \left( \frac{x + 8}{5} \right)^2 = \frac{(x + 8)^2}{25} \][/tex]

Next, multiply by 2:
[tex]\[ y = 2 \cdot \frac{(x + 8)^2}{25} + 6 \][/tex]
[tex]\[ y = \frac{2(x + 8)^2}{25} + 6 \][/tex]

4. Expand and simplify:

Expand [tex]\( (x + 8)^2 \)[/tex]:
[tex]\[ (x + 8)^2 = x^2 + 16x + 64 \][/tex]

Substitute back into the equation:
[tex]\[ y = \frac{2(x^2 + 16x + 64)}{25} + 6 \][/tex]

Distribute the 2:
[tex]\[ y = \frac{2x^2 + 32x + 128}{25} + 6 \][/tex]

Combine into a single fraction and simplify:
[tex]\[ y = \frac{2x^2 + 32x + 128}{25} + \frac{150}{25} \][/tex]
[tex]\[ y = \frac{2x^2 + 32x + 128 + 150}{25} \][/tex]
[tex]\[ y = \frac{2x^2 + 32x + 278}{25} \][/tex]

Thus, the rectangular form of the given parametric equations is:
[tex]\[ y = \frac{2x^2 + 32x + 278}{25} \][/tex]

Comparing this result to the given choices:
- [tex]\( y = \frac{2}{25} x^2 + \frac{32}{25} x + \frac{278}{25} \)[/tex]

We see that they match. Therefore, the correct answer is:

[tex]\[ y = \frac{2}{25} x^2 + \frac{32}{25} x + \frac{278}{25} \][/tex]