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2 years ago

If a = 5 and b=2 then find the value of - 2ab and - 3a+b

Mathematics

2 answers:

attashe74 [19]2 years ago

7 0

Answer:

-2ab = -20
-3a + b = -13

Concept:

Here, we need to understand the idea of evaluation.

When encountering questions that gave you an expression with variables, then stated: "If x = a, y = b, z = c" (a, b, c are all constants), this means you should substitute the value given for each variable back to the expression.

Solve:

<h2>PART I: Find the value of -2ab</h2>

<u>Given information</u>

a = 5

b = 2

<u>Given expression</u>

-2ab

<u>Substitute values into the expression</u>

-2 (5) (2)

<u>Simplify by multiplication</u>

=-10 (2)

= $\boxed{-20}$

--------------------------------------------------------

<h2>PART II: Find the value of -3a + b</h2>

<u>Given information</u>

a = 5

b = 2

<u>Given expression</u>

-3a + b

<u>Substitute values into the expression</u>

-3 (5) + (2)

<u>SImplify by multiplication</u>

=-15 + (2)

<u>Simplify by addition</u>

= $\boxed{-13}$

Hope this helps!! :)

Please let me know if you have any questions

dusya [7]2 years ago

3 0

-2ab = -2(5)(2) = -20
-3a+b = -3(5)+2 = -13

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After being treated with chemotherapy, the radius of the tumor decreased by 23%. What is the corresponding percentage decrease i

Crazy boy [7]

Answer:

The volume of the tumor experimented a decrease of 54.34 percent.

Step-by-step explanation:

Let suppose that tumor has an spherical geometry, whose volume ( $V$ ) is calculated by:

$V = \frac{4\pi}{3}\cdot R^{3}$

Where $R$ is the radius of the tumor.

The percentage decrease in the volume of the tumor ( $\%V$ ) is expressed by:

$\%V = \frac{\Delta V}{V_{o}} \times 100\,\%$

Where:

$\Delta V$ - Absolute decrease in the volume of the tumor.

$V_{o}$ - Initial volume of the tumor.

The absolute decrease in the volume of the tumor is:

$\Delta V = V_{o}-V_{f}$

$\Delta V = \frac{4\pi}{3}\cdot (R_{f}^{3}-R_{o}^{3})$

The percentage decrease is finally simplified:

$\%V = \left[1-\left(\frac{R_{f}}{R_{o}}\right)^{3} \right]\times 100\,\%$

Given that $R_{o} = R$ and $R_{f} = 0.77\cdot R$ , the percentage decrease in the volume of tumor is:

$\%V = \left[1-\left(\frac{0.77\cdot R}{R}\right)^{3} \right]\times 100\,\%$

$\%V = 54.34\,\%$

The volume of the tumor experimented a decrease of 54.34 percent.

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3 years ago

A rhombus has four 6-inch sides and two 120-degree angles. From one of the vertices of the obtuse angles, the two latitudes are

nikitadnepr [17]

Answer:

Area(A)=Area(C)= $9 in^{2}$

Area(B)= $13.2 in^{2}$

Step-by-step explanation:

We begin with finding the angles a and b that from the drawing attached you can see that a=b.

Now, the sum of the internal angles of a rhomboid is equal to 360 degrees, with that we have:

120+120+a+b=360

240+2a=360

2a=120

a=60=b

Next, in the image you can see that the lines coming from the angle at the top 120 degrees vertex, divide the opposite sides by half, thus making two triangles with one side of 6 in and another of 3 in.

We can say from the drawing as well:

Area(A)+Area(B)+Area(C)=Area(rhomboid)

But, we can also say that Area(A)=Area(C)

So, starting with Area(A)

Area(A)=Area(triangle)= $\frac{b*h}{2}$ = $\frac{6*3}{2}$ = $9 in^{2}$

We can then calculate the area B, a rhomboid, or better, take the Total area of the figure and subtract the area of the two triangles.

Area(B)=Area(rhomboid)-Area(A)-Area(C)

Area(rhomboid)=b*h where b=6in and h is the perpendicular distance from the base to the top.

$h=[tex]6*cos(30)=5.20in$ The 30 degrees come from: 120-30-60=30, since the latitudes split the 120 angle in two equal parts and one that is the half of the obtuse angle.