All categories

3 years ago

I need help please and thank you

Mathematics

2 answers:

Amanda [17]3 years ago

8 0

Answer:

-2,400

Step-by-step explanation:

since they are in parentheses u multiple them together. a positive number × a negative number is a negative number.

Salsk061 [2.6K]3 years ago

8 0

Answer:

-2,480

Step-by-step explanation:

(31)(-80)

= -2,480

plus × minus = minus

You might be interested in

A beam of electrons with energies of 250 MeV is scattered through an angle of 100 by a heavy nucleus. It is found that the diffe

WITCHER [35]

Answer: The radii of atomic nuclei are of the order of 50×10^-15 to the negative 15th power.

4 0

2 years ago

HALLP QUICKKKK

Rina8888 [55]

To solve this we are going to use the formula for speed: $S= \frac{d}{t}$
where
$S$ is the speed
$d$ is the distance
$t$ is the time

Let $S_{l}$ be the speed of the boat in the lake, $S_{a}$ the speed of the boat in the river, $t_{l}$ the time of the boat in the lake, and $t_{a}$ the time of the boat in the river.

We know for our problem that the current of the river is 2 km/hour, so the speed of the boat in the river will be the speed of the boat in the lake minus 2km/hour:
 $S_{a}=S_{l}-2$
We also know that in the lake the boat sailed for 1 hour longer than it sailed in the river, so:
 $t_{l}=t_{a}+1$

Now, we can set up our equations.
Speed of the boat traveling in the river:
 $S_{a}= \frac{6}{t_{a} }$
But we know that $S_{a}=S_{l}-2$ , so:
$S_{l}-2= \frac{6}{t_{a} }$ equation (1)

Speed of the boat traveling in the lake:
$S_{l}= \frac{15}{t_{l} }$
But we know that $t_{l}=t_{a}+1$ , so:
$S_{l}= \frac{15}{t_{a}+1}$ equation (2)

Solving for $t_{a}$ in equation (1):
$S_{l}-2= \frac{6}{t_{a} }$
$t_{a}= \frac{6}{S_{l}-2}$ equation (3)

Solving for $t_{a}$ in equation (2):
$S_{l}= \frac{15}{t_{a}+1}$
$t_{a}+1= \frac{15}{S_{l}}$
$t_{a}=\frac{15}{S_{l}}-1$
$t_{a}= \frac{15-S_{l}}{S_{l}}$ equation (4)

Replacing equation (4) in equation (3):
$t_{a}= \frac{6}{S_{l}-2}$
$\frac{15-S_{l}}{S_{l}}=\frac{6}{S_{l}-2}$

Solving for $S_{l}$ :
$\frac{15-S_{l}}{S_{l}}=\frac{6}{S_{l}-2}$
$(15-S_{l})(S_{l}-2)=6S_{l}$
$15S_{l}-30-S_{l}^2+2S_{l}=6S_{l}$
$S_{l}^2-11S_{l}+30=0$
$(S_{l}-6)(S_{l}-5)=0$
$S_{l}=6$ or $S_{l}=5$

We can conclude that the speed of the boat traveling in the lake was either 6 km/hour or 5 km/hour.

3 0

4 years ago

Write the equation in point slope form for the line that contains the points (-2,-3), (4,3)

Minchanka [31]

Answer:

y + 3 = 1 ⋅ (x + 2).

Step-by-step explanation:

Find the equation using point-slope formula.

Slope-intercept form:

y = x − 1

Point-slope form:

y + 3 = 1 ⋅ (x + 2)

5 0

3 years ago

Fill in the blanks to make an arithmetic sequence

Arlecino [84]

-----------------------------------------
General Equation:
-----------------------------------------
$T_n = a_1 + d(n - 1)$

-----------------------------------------
Find d :
-----------------------------------------
$a_1 = 11, T_7 = 79,$
$T_7 = 11 + d(7 - 1)$
$-79 = 11 + 6d$
$6d = -79 - 11$
$6d = -90$
$d = -15$

-----------------------------------------
Find general equation :
-----------------------------------------
$T_n = 11 + (-15)(n - 1)$
$T_n = 11 -15n + 15$
$T_n = 26 -15n$

-----------------------------------------
Find the sequence :
-----------------------------------------
$T_1 = 26 - 15(1) = 11$
$T_2 = 26 - 15(2) = -4$
$T_3 = 26 - 15(3) = -19$
$T_4 = 26 - 15(4) = -34$
$T_5 = 26 - 15(5) = -49$
$T_6 = 26 - 15(6) = -64$
$T_7 = 26 - 15(7) = -79$

---------------------------------------------------------
Answer: 11, -4, -19, -34, -49, -64, -79
---------------------------------------------------------

4 0

3 years ago

(1½ * $8.40) * 7 = x

stepladder [879]

X = 88.2

Don't forget to make me brainliest answer.

5 0

3 years ago