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>
565 is the correct answer
Answer:
Joshua can spend up to 3.21 on a card.
Step-by-step explanation:
is the correct equation because Joshua is spending 21.79 on flowers, a certain amount on the card, and the maximum he can spend is 25. That is why you use the less than or equal to sign.
To solve, first subtract 21.79 from both sides to get: 
. This means that Joshua can spend up to 3.21 on a card.
Hope it helps!
To convert from decimal to percent, just multiply the decimal value by 100. In this example we have: 0.768 × 100 = 76.8%
The ease way:
1) Move the decimal point two places to the right: 0.768 → 7.68 → 76.8.
2) Add a % sign: 76.8%
"<u>Answer: 76.8%"</u>
Hope this helps!
Thanks!
-Charlie
Answer:
Yes, 500 texts.
Step-by-step explanation:
If you write out the equations, you can just set them up equal to each other and simplify.
A = .05x + 20
B = .07x + 10
.05x + 20 = .07x + 10 (subtract 10 from both sides)
.05x + 10 = .07x (subtract .05x from both sides)
10 = .02x (multiply both sides by 50
x = 500 texts
