All categories

2 years ago

Can someone help me do this problem and explain it to me step by step? If so I’ll mark you brainliest

Mathematics

1 answer:

Advocard [28]2 years ago

7 0

Answer:

-21

Step-by-step explanation:

1) if r = -4

Substitute r = -4 in 3r - 9

= 3 * (-4) - 9

= -12 - 9

= -21

2) ( 4 / 7 ) * x = 16

4 * x = 16 * 7

x = 4 * 7

x = 28

You might be interested in

Subtract 6 from me. Then multiply by 2. If you subtract 40 and then divide by 4, you get 8. What number am I?

aliina [53]

Answer:

Step-by-step explanation:

Let the number be "x"

We translate the word equation to algebraic equation.

First,

subtract 6 from me, so we have:

x - 6

Now,

Multiply by 2, so we have:

2(x-6)

Now,

Subtract 40, then divide by 4:

$\frac{2(x-6)-40}{4}$

Now, you get "8", so equate this to 8, we get:

$\frac{2(x-6)-40}{4}=8$

We now solve using algebra:

$\frac{2(x-6)-40}{4}=8\\2(x-6)-40=4*8\\2(x-6)-40=32\\2x-12-40=32\\2x-52=32\\2x=32+52\\2x=84\\x=42$

The number is 42

7 0

3 years ago

David used the measuring cup show to measure milk for a batch of muffins. He needs to make 12 batches of muffins for a fund rais

lozanna [386]

16x12=192
Yes, if he only uses one cup per batch

5 0

2 years ago

Read 2 more answers

Which is the graph of g(x)?

Solnce55 [7]

Answer:

the answer is letter D

Step-by-step explanation:

3 0

2 years ago

Drag each interval to a box to show if the function shown is increasing, decreasing, or neither over that interval. 6 4 10 8 1 t

Kitty [74]

Answer:

Function (4 < x < 6) and (8 < x < 10) is decreasing

Function (1 < x < 4) and (6 < x < 8) is increasing

Function (10 < x < 14) is neither increasing nor decreasing

Step-by-step explanation:

The question is incomplete. The complete question has been added as an attachment.

From the graph:

x-axis (horizontal), y-axis (vertical)

Note: moving from negative bigger number to negative smaller number is an increase.

Moving from negative smaller number to negative bigger number is a decrease.

6 < x < 8: on the x-axis, from number +6 to +8, you find on the y-axis the line moved from -7 to -4. That is an increase.

4 < x < 6: on the x-axis, from number +4 to +6, you find on the y-axis the line moved from -3 to -7. That is a decrease.

10 < x < 14: on the x-axis, from number +10 to +14, you find on the y-axis the line moved from -5 to -5. It remained on the same number. It is neither increasing nor decreasing.

8 < x < 10: on the x-axis, from number +8 to +10, you find on the y-axis the line moved from -4 to -5. That is a decrease

1 < x < 4: on the x-axis, from number +1 to +4, you find on the y-axis the line moved from -11 to -3. That is an increase.

4 0

2 years ago

The illuminance of a surface varies inversely with the square of its distance from the light source.If the illuminance of a surf

VashaNatasha [74]

Answer:

Distance between the surface and source of light will be increased by 6 meters.

Step-by-step explanation:

The illuminance of a surface varies inversely with the square of ts distance from the light source.

Let illuminance of the surface = x lumens per square meter

and distance from a light source = y meter.

Now x ∝ $\frac{1}{y^{2} }$

Or $x=\frac{k}{y^{2} }$ [k = proportionality constant]

Now we will find the value of k.

k = xy²

k = 120×(6)²

k = 4320

We have to calculate the distance of the source if illuminance of the surface is 30 lumens per square meter.

$30=\frac{4320}{y^{2}}$

y² = $\frac{4320}{30}$

y² = 144

y = √144 = 12 meters

So the source of the light will be shifted away from the surface = 12 - 6 = 6 meters.

6 0

2 years ago