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3 years ago

Fred bought 7 new baseball trading cards to add to his collection. The next

1 answer:

4 0

His dog ate 1/2 of his collection, this means that there are only 33 left. If I multiply 33x2, I will get 66. Therefore, Fred started with 66 cards.

(If you’re not counting the cards he purchased, then Fred would have 59 cards.)

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2. Carl needs 15 hours longer than Jennifer to paint a room. If they work together, they can complete the job in 4 hours. Explai

nasty-shy [4]

Answer:

Jennifer would complete the job on her own in 5 hours.

Step-by-step explanation:

Solving a quadratic equation:

Given a second order polynomial expressed by the following equation:

$ax^{2} + bx + c, a\neq0$ .

This polynomial has roots $x_{1}, x_{2}$ such that $ax^{2} + bx + c = a(x - x_{1})*(x - x_{2})$ , given by the following formulas:

$x_{1} = \frac{-b + \sqrt{\Delta}}{2*a}$

$x_{2} = \frac{-b - \sqrt{\Delta}}{2*a}$

$\Delta = b^{2} - 4ac$

Rates

The together rate is the sum of their separates rate.

We have that:

Jennifer takes x hours to complete the job on her own, so her rate is 1/x.

Carl needs 15 hours longer than Jennifer, that is, 15 + x hours, so his rate is 1/(15+x).

The together rate is 1/4. So

$\frac{1}{4} = \frac{1}{x} + \frac{1}{15+x}$

$\frac{1}{4} = \frac{15 + x + x}{x(15+x)}$

$\frac{1}{4} = \frac{15 + 2x}{x(15+x)}$

Applying cross multiplication.

$x^2 + 15x = 4(15 + 2x)$

$x^2 + 15x = 60 + 8x$

$x^2 + 7x - 60 = 0$

Quadratic equation with $a = 1, b = 7, c = -60$ . So

$\Delta = 7^{2} - 4*1*60 = 289$

$x_{1} = \frac{-7 + \sqrt{289}}{2} = 5$

$x_{2} = \frac{-7 - \sqrt{289}}{2} = -12$

Since the time to complete the job has to be a positive value.

Jennifer would complete the job on her own in 5 hours.

4 0

3 years ago

How do I solve 4/9+9/2 and write my answer as a mixed number?

jenyasd209 [6]

9 has factors of 3*3.

2 is prime, so no factors.

from those two denominators, we can get the LCD of hmmm simply their product, namely 18.

$\bf \cfrac{4}{9}+\cfrac{9}{2}\implies \stackrel{\textit{using the LCD of 18}}{\cfrac{(2)4+(9)9}{18}}\implies \cfrac{8+81}{18}\implies \cfrac{89}{18}\implies 4\frac{17}{18}$