By "y = −9x2 − 2x" I assume you meant <span>y = −9x^2 − 2x (the "^" symbol represents exponentiation).
Let's find the first derivative of y with respect to x: dy/dx = -18x - 2. This is equivalent to the slope of the tangent line to the (parabolic) curve. Now let this derivative (slope) = 0 and solve for the critical value: -18x - 2 = 0, or
-18x = 2. Solving for x, x = -2/18, or x = -1/9.
When x = -1/9, y = -9(-1/9)^2 - 2(-1/9). This simplifies to y = -9/9 + 2/9, or
y = -7/9.
The only point at which the tangent to the curve is horiz. is (-1/9,-7/9).</span>
3/4 I believe since 6 1/4- 51/2 is 3/4
<h3>
Answer: 30 inches</h3>
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Explanation:
x = unknown width
For this rectangle, there are 2 sides of length x, and 2 sides of length 17.
The perimeter is P = 2x+2*17 = 2x+34
Set this equal to the given perimeter (94) and solve for x.
2x+34 = 94
2x = 94-34
2x = 60
x = 60/2
x = 30
The TV is 30 inches wide
