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3 years ago

14

A plumber charges a $75 flat fee for jobs lasting up to an hour and $30 for each hour of labor after the first hour. which expre

ssion models the cost of a job lasting h hours, when h is greater than 1?

2 answers:

larisa [96]3 years ago

6 0

Answer:

75+30h

Step-by-step explanation:

professor190 [17]3 years ago

4 0

Answer:

75+30h

Step-by-step explanation:

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What is the sum of 20x^2-10x-30

ivann1987 [24]

Answer:

The sum of the roots is 0.5

Step-by-step explanation:

<u><em>The correct question is</em></u>

What is the sum of the roots of 20x^2-10x-30

we know that

In a quadratic equation of the form

$ax^{2} +bx+c=0$

The sum of the roots is equal to

$-\frac{b} {a}$

in this problem we have

$20x^{2} -10x-30=0$

so

$a=20\\b=-10\\c=-30$

substitute

$-\frac{(-10)} {20}=0.5$

<u><em>Verify</em></u>

Find the roots of the quadratic equation

The formula to solve a quadratic equation is equal to

$x=\frac{-b\pm\sqrt{b^{2}-4ac}} {2a}$

$a=20\\b=-10\\c=-30$

substitute

$x=\frac{-(-10)\pm\sqrt{-10^{2}-4(20)(-30)}} {2(20)}$

$x=\frac{10\pm\sqrt{2,500}} {40}$

$x=\frac{10\pm50} {40}$

$x=\frac{10+50} {40}=1.5$

$x=\frac{10-50} {40}=-1$

The roots are x=-1 and x=1.5

The sum of the roots are

$-1+1.5=0.5$ ----> is ok

5 0

3 years ago

Use a table of values to estimate the value of the limit. Confirm your result graphically by graphing the function with a graphi

il63 [147K]

Hello,

$\lim_{x \to 0}\dfrac{ \sqrt{x+25}-5}{x}\\\\$

$=\lim_{x \to 0}\dfrac{(\sqrt{x+25}-5)*(\sqrt{x+25}+5)}{x*(\sqrt{x+25}+5)}\\\\$

$=\lim_{x \to 0}\dfrac{x+25-25)}{x*(\sqrt{x+25}+5)}\\\\$

$=\dfrac{1}{10}$

4 0

3 years ago

Please Help. 25 points. <br>

vodomira [7]

Answer:

$\boxed{x = 7, y = 9, z = 68}$

Step-by-step explanation:

We must develop three equations in three unknowns.

I will use these three:

$\begin{array}{lrcll}(1) & 8x + 13y +7 & = & 180 & \\(2)& 9x - 7 + 13y +7 & = & 180 & \\(3)& 8x + 5y - 11 + z & = & 180 &\text{We can rearrange these to get:}\\(4)& 8x + 13y & = & 173 &\\(5) & 9x + 13y & = & 180 & \\(6)& 8x + 5y + z & = & 169 & \\(7)& x & = & \mathbf{7} & \text{Subtracted (4) from (5)} \\\end{array}$

$\begin{array}{lrcll}& 8(7) + 13y & = & 173 & \text{Substituted (7) into (4)} \\& 56 + 13y & = & 173 & \text{Simplified} \\& 13y & = & 117 & \text{Subtracted 56 from each side} \\(8)& y & =& \mathbf{9}&\text{Divided each side by 13}\\& 8(7) + 5(9) + z & = & 169 & \text{Substituted (8) and (7) into (6)} \\& 56 + 45 + z& = & 169 & \text{Simplified} \\& 101 + z& = & 169 & \text{Simplified} \\&z& = & \mathbf{68} & \text{Subtracted 101 from each side}\\\end{array}$

$\boxed{\mathbf{ x = 7, y = 9, z = 68}}$

4 0

3 years ago

Factor tree 50 and 75 math

olga55 [171]

Answer:

2 x 25 (50)

3 x 25 (75)

Step-by-step explanation:

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3 years ago

What square root expression represents the golden ratio?

Juli2301 [7.4K]

I believe the phi ratio^2 = 1 + phi ratio
phi ratio = 1.6180339
phi ratio^2 = 2.6180339

4 0

2 years ago