Please help!!! I will mark best answer!

When the sum of \, 528 \, and three times a positive number is subtracted from the square of the number, the result is \, 120. F

aleksandr82 [10.1K]

Let $x$ be the unknown number. So, three times that number means $3x$ , and the square of the number is $x^2$

We have to sum 528 and three times the number, so we have $528+3x$

Then, we have to subtract this number from $x^2$ , so we have

$x^2-(3x+528)$

The result is 120, so the equation is

$x^2 - 3x - 528 = 120 \iff x^2 - 3x - 648 = 0$

This is a quadratic equation, i.e. an equation like $ax^2+bx+c=0$ . These equation can be solved - assuming they have a solution - with the following formula

$x_{1,2} = \dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$

If you plug the values from your equation, you have

$x_{1,2} = \dfrac{3\pm\sqrt{9-4\cdot(-648)}}{2} = \dfrac{3\pm\sqrt{9+2592}}{2} = \dfrac{3\pm\sqrt{2601}}{2} = \dfrac{3\pm51}{2}$

So, the two solutions would be

$x = \dfrac{3+51}{2} = \dfrac{54}{2} = 27$

$x = \dfrac{3-51}{2} = \dfrac{-48}{2} = -24$

But we know that x is positive, so we only accept the solution $x = 27$

6 0

3 years ago

what do I do on C it says assess the reasonableness of your answer in B and use your estimate from A to explain

poizon [28]

I think that the answer is B<span />

5 0

4 years ago

Plz hurry I will give 17 points

UNO [17]

Your answer should be organize, correct me if I’m wrong !

6 0

3 years ago

Read 2 more answers

The size of the left upper chamber of the heart is one measure of cardiovascular health. When the upper left chamber is enlarged

Temka [501]

Answer:

a) 0.283 or 28.3%

b) 0.130 or 13%

c) 0.4 or 40%

d) 30.6 mm

Step-by-step explanation:

z-score of a single left atrial diameter value of healthy children can be calculated as:

z= $\frac{X-M}{s}$ where

X is the left atrial diameter value we are looking for its z-score

M is the mean left atrial diameter of healthy children (26.7 mm)

s is the standard deviation (4.7 mm)

Then

a) proportion of healthy children who have left atrial diameters less than 24 mm

=P(z<z*) where z* is the z-score of 24 mm

z*= $\frac{24-26.7}{4.7}$ ≈ −0.574

And P(z<−0.574)=0.283

b) proportion of healthy children who have left atrial diameters greater than 32 mm

= P(z>z*) = 1-P(z<z*) where z* is the z-score of 32 mm

z*= $\frac{32-26.7}{4.7}$ ≈ 1.128

1-P(z<1.128)=0.8703=0.130

c) proportion of healthy children have left atrial diameters between 25 and 30 mm

=P(z(25)<z<z(30)) where z(25), z(30) are the z-scores of 25 and 30 mm

z(30)= $\frac{30-26.7}{4.7}$ ≈ 0.702

z(25)= $\frac{25-26.7}{4.7}$ ≈ −0.362

P(z<0.702)=0.7587

P(z<−0.362)=0.3587

Then P(z(25)<z<z(30)) =0.7587 - 0.3587 =0.4

d) to find the value for which only about 20% have a larger left atrial diameter, we assume

P(z>z*)=0.2 or 20% where z* is the z-score of the value we are looking for.

Then P(z<z*)=0.8 and z*=0.84. That is

0.84= $\frac{X-26.7}{4.7}$ solving this equation for X we get X=30.648

5 0

3 years ago

Translate this sentence into an equation.

ElenaW [278]

Answer:

The product of Victor's age and 7 is 84 in equation form is 7v=84

Step-by-step explanation:

Let v be the Victor's age.

We are supposed to Translate this sentence into an equation

The product of Victor's age and 7 is 84

Victor's age = v

Product of victor's age and 7 = $7 \times v$

We are given that their product is 84

So, $7 \times v =84$

Hence The product of Victor's age and 7 is 84 in equation form is 7v=84

7 0

3 years ago