Which of the following is equal to the fraction below

The solutions to (r + 4) - 2 = 7 are

Nina [5.8K]

Answer:

r=5

Step-by-step explanation:

r+2=7

r=5

3 0

2 years ago

Read 2 more answers

Evaluate the double integral.

Fynjy0 [20]

Answer:

$\iint_D 8y^2 \ dA = \dfrac{88}{3}$

Step-by-step explanation:

The equation of the line through the point $(x_o,y_o)$ & $(x_1,y_1)$ can be represented by:

$y-y_o = m(x - x_o)$

Making m the subject;

$m = \dfrac{y_1 - y_0}{x_1-x_0}$

∴

we need to carry out the equation of the line through (0,1) and (1,2)

i.e

y - 1 = m(x - 0)

y - 1 = mx

where;

$m= \dfrac{2-1}{1-0}$

m = 1

Thus;

y - 1 = (1)x

y - 1 = x ---- (1)

The equation of the line through (1,2) & (4,1) is:

y -2 = m (x - 1)

where;

$m = \dfrac{1-2}{4-1}$

$m = \dfrac{-1}{3}$

∴

$y-2 = -\dfrac{1}{3}(x-1)$

-3(y-2) = x - 1

-3y + 6 = x - 1

x = -3y + 7

Thus: for equation of two lines

x = y - 1

x = -3y + 7

i.e.

y - 1 = -3y + 7

y + 3y = 1 + 7

4y = 8

y = 2

Now, y ranges from 1 → 2 & x ranges from y - 1 to -3y + 7

∴

$\iint_D 8y^2 \ dA = \int^2_1 \int ^{-3y+7}_{y-1} \ 8y^2 \ dxdy$

$\iint_D 8y^2 \ dA =8 \int^2_1 \int ^{-3y+7}_{y-1} \ y^2 \ dxdy$

$\iint_D 8y^2 \ dA =8 \int^2_1 \bigg ( \int^{-3y+7}_{y-1} \ dx \bigg) dy$

$\iint_D 8y^2 \ dA =8 \int^2_1 \bigg ( [xy^2]^{-3y+7}_{y-1} \bigg ) \ dy$

$\iint_D 8y^2 \ dA =8 \int^2_1 \bigg ( [y^2(-3y+7-y+1)]\bigg ) \ dy$

$\iint_D 8y^2 \ dA =8 \int^2_1 \bigg ([y^2(-4y+8)] \bigg ) \ dy$

$\iint_D 8y^2 \ dA =8 \int^2_1 \bigg ( -4y^3+8y^2 \bigg ) \ dy$

$\iint_D 8y^2 \ dA =8 \bigg [\dfrac{ -4y^4}{4}+\dfrac{8y^3}{3} \bigg ]^2_1$

$\iint_D 8y^2 \ dA =8 \bigg [ -y^4+\dfrac{8y^3}{3} \bigg ]^2_1$

$\iint_D 8y^2 \ dA =8 \bigg [ -2^4+\dfrac{8(2)^3}{3} + 1^4- \dfrac{8\times (1)^3}{3}\bigg]$

$\iint_D 8y^2 \ dA =8 \bigg [ -16+\dfrac{64}{3} + 1- \dfrac{8}{3}\bigg]$

$\iint_D 8y^2 \ dA =8 \bigg [ -15+ \dfrac{64-8}{3}\bigg]$

$\iint_D 8y^2 \ dA =8 \bigg [ -15+ \dfrac{56}{3}\bigg]$

$\iint_D 8y^2 \ dA =8 \bigg [ \dfrac{-45+56}{3}\bigg]$

$\iint_D 8y^2 \ dA =8 \bigg [ \dfrac{11}{3}\bigg]$

$\iint_D 8y^2 \ dA = \dfrac{88}{3}$

4 0

2 years ago

How to find the area of this figure

stiv31 [10]

Answer:

45 square units.

Step-by-step explanation:

Applying the pythagoras theorem:

Base of the bigger triangle = $\sqrt{15^2 - 9^2}$ = $\sqrt{144}$ = 12 units

Area of a triangle is given by $\frac{1}{2}$ × base × height

The area of the bigger triangle is $\frac{1}{2}$ × 12 × 9 = 54 square units.

The area of the smallest triangle is $\frac{1}{2}$ × (12 - 10) × 9 = 9 square units.

The area of the figure( required triangle) is 54 - 9 = 45 square units.

3 0

2 years ago

A dog jumps straight up. Y=-16t^2+20t models the motion of the dog, where "t" is the time in seconds and "y" is the height of th

alina1380 [7]

Answer:

Step-by-step explanation:

The motion of the dolphin is quadratic

i.e y=-16t²+20t

To get the maximum height the dolphin will reach

We need to find the point of inflexion. i.e dy/dt=0

dy/dt=-32t+20

Then set dy/dt=0

0=-32t+20

Then, -32t=-20

t=0.625

Let find d²y/dt²

d²y/dt²=-32. Since this is negative then the point t=0.625 is the maximum point the dolphin can reach

Then substitute t=0.625 into y

y=-16t²+20t

y=-16(0.625)²+20(0.625)

y=6.25ft

Then the maximum height the dolphin can reach is 6.25ft

Using discriminant

Formular method

y=-16t²+20t

So the dog height y<7

y=-16t²+20t <7

-16t²+20t-7<0

a=-16, b= 20. c=-7

t=(-b±√b²-4ac)/2a

Using the a, b and c direct for the discriminant

D=b²-4ac

D=20²-4×-16×-7

D=-48

Which is a complex number

Then the dolphin can reach the height

Then we need to model the D to be greater than 0

Therefore,

D>0

b²-4ac>0

We cannot do anything to a and b it is already given

a=-16, b=20

(20)²-4(-16c)>0

400+64c>0

64c>-400

Then

c>-6.25

Divide both side by - and the inequality sign will change

Therefore -c<6.25

So the dog height y<6.25

y=-16t²+20t <6.25

Therefore the maximum height is 6.25.

If it is greater than that then, we are going to have a complex root movement which is not possible for the dolphin .

5 0

3 years ago

thirty five percent of the revenue produced at the auction will go to the charity. the morning participants spent an average of

spin [16.1K]

I'm not sure that I am 100% right but I'll give it a shot.
50+75= 125*0.35=43.75
$43.75

4 0

2 years ago