Which equation represents a slope of −4<br> and y-intercept of (0, 2) ?

A car travels for 4(t+3) hours at a constant speed of 10(t+3) km/h. If the total distance travelled by the car is 810 km, find t

IceJOKER [234]

Step-by-step explanation:

$\because \: time \times speed = distance \\ \therefore \: 4(t + 3) \times 10(t + 3) = 810 \\ \therefore \: 4(t + 3)^{2} = 81 \\ \therefore \: \{2(t + 3) \}^{2} = {9}^{2} \\ \therefore \: \{2(t + 3) \} = {9} \\ \therefore \: t + 3 = \frac{9}{2} \\ \therefore \: t = \frac{9}{2} - 3 \\ \therefore \: t = \frac{9 - 6}{2} \\ \therefore \: t = \frac{3}{2} \\ \therefore \: t = 1.5 \: hrs \\$

$\because \: time \times speed = distance \\ \therefore \: 4(t + 3) \times 10(t + 3) = 810 \\ \therefore \: 4(t + 3)^{2} = 81 \\ \therefore \: \{2(t + 3) \}^{2} = {9}^{2} \\ \therefore \: \{2(t + 3) \} = {9} \\ \therefore \: t + 3 = \frac{9}{2} \\ \therefore \: t = \frac{9}{2} - 3 \\ \therefore \: t = \frac{9 - 6}{2} \\ \therefore \: t = \frac{3}{2} \\ \therefore \: t = 1.5 \: hrs \\ speed \: of \: car = 10(t + 3) \\ \hspace{60 pt} = 10(1.5 + 3) \\ \hspace{60 pt}= 10 \times 4.5 \\ \red{ \boxed{ \bold{ \therefore \: speed \: of \: car = 45 \:km/ h}}} \\$

3 0

3 years ago

Which of the following sets is NOT closed under addition.

Veronika [31]

Answer:

Step-by-step explanation:

The odd numbers.

Suppose you have 31 and 27 when you add these two together, you get 58 which is not an odd number.

If you need a more mathematical proof, you could do it this way.

2x+1

2x is even. Anything multiplied by 2 is even. When you add 1 you get an odd number

So continue on

2y + 1 is the other number.

2x + 1 + 2y + 1 = 2(x + y) + 2

2 (x + y ) is even. When you add 2 to it, nothing changes. The result is still even.

7 0

3 years ago

I'm really confused about this question about Solving Systems by Elimination

velikii [3]

Answer:

x=10

y=2

Step-by-step explanation:

1)add the equations and find what x is.

x-y=8

+x+y=12

—————

2x=20

— —

2 2

x=10

3)fill in x for the second equation.

x+y=12

since x=10,replace x with 10.

10+y=12.

subtract 19 from both sides.

10+y=12

-10 -10

—————-

y=2

4 0

2 years ago

Mathhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

mr Goodwill [35]

It's the first choice.Correlation that implies causation

3 0

3 years ago

Read 2 more answers

Simplify the expression

MaRussiya [10]

11) 7 + -10+(4(5+-3)) = 7+-10+8=5

12) (12 +-10)+3x+-1(2x+4x), 12+-10x+3x+-2x+-4x = 12+-13x

5 0

2 years ago

Read 2 more answers

Which equation represents a slope of −4 and y-intercept of (0, 2) ?