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3 years ago

HeLp PleAsE!!!!!!!!!!!!!!!

Mathematics

1 answer:

VLD [36.1K]3 years ago

3 0

Answer: the third

Step-by-step explanation:

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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

2 years ago

Ella used 37.2 pounds of apples to make applesauce . She used one -tenth as a many pounds of sugar as pounds of apples . How man

sukhopar [10]

You would have to divide 37.2 by 10. The answer would be 3.72.

3 0

2 years ago

Help please solve for the given variable<br> -8 (7k - 5) + 7(7k - 7) = 1 - 5k - k - 7

cluponka [151]

- 8(7k-5) + 7(7k-7) = 1 - 5k - k - 7
- 56k + 40 + 49k - 49 = 1 - 6k - 7
13k = 3
k = 3/13

i am a mathematics teacher. if anything to ask please pm me

8 0

3 years ago

1. A baseball coach graphs some data and finds the line of

Vlada [557]

The answer to this is 35 because i did caculation and thats the answer it gave me

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2 years ago

During the big storm, 30 in. of snow fell in 7 h. Find the rate of snowfall in inches per hour.

andrew-mc [135]

30 divided by 7 is 4.2z
It snowed 4.2 inches per hour

3 0

2 years ago