Please help!!!!!!!!!!!! !!!

Solve each question using the quadratic formula? X2+4x+3=0

Sergeeva-Olga [200]

x=−1 or x=−3 i think lol

8 0

3 years ago

David bought 3 dvds and 4 books for $40 at a yard sale. Anna bought 1 dvd and 6 books for $18. How much did each dvd and book co

Ber [7]

Answer:

A book is worth $1 and a DVD is worth $12.

Step-by-step explanation:

The equations (2 unknowns and two equations, d is for a DVD and b is for a book):

For David: 3d+4b=40

For Anna: d+6b=18

Now multiply the second equation with -3 and add to the first equation:

3d+4b=40

−3d−18b=−54

Combined equation: −14b=−14 and b=1 (means that each book is worth $1).

Now for DVD price, use the second equation:

d=18−6 or d=12 (means that each DVD is worth $12).

A book is worth $1 and a DVD is worth $12.

8 0

3 years ago

The equation of line L is y=5x+1

vovikov84 [41]

Answer:

see explanation

Step-by-step explanation:

Parallel lines have equal slopes.

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

L₁ is y = 5x + 1 ← in slope- intercept form

with slope m = 5

L₂ is 2y - 10x + 3 = 0 ( subtract - 10x + 3 from both sides )

2y = 10x - 3 ( divide all terms by 2 )

y = 5x - $\frac{3}{2}$ ← in slope- intercept form

with slope m = 5

Since L₁ and L₂ have equal slopes then they are parallel lines

3 0

3 years ago

An air balloon begins it's decent to the ground at 1000 ft above the ground and falls at a rate of 50 ft per minute. Select all

Radda [10]

Answer:

The correct options are 3, 4 and 5.

Step-by-step explanation:

It is given that an air balloon begins it's decent to the ground at 1000 ft above the ground and falls at a rate of 50 ft per minute.

It means the initial height of air balloon is 1000. So, the y-intercept is (0,1000).

The ball falls at a rate of 50 ft per minute. So, the rate of change is

$m=-50$

The height of balloon is defined as

$h(x)=-50x+1000$ $[\because y=mx+b]$

Where, x is time in minutes.

The balloon will reach the ground when h(x)=0

$0=-50x+1000$

$50x=1000$

$x=20$

Therefore the options 3, 4 and 5 are correct.

4 0

3 years ago

If a cup of coffee has temperature 95∘C in a room where the temperature is 20∘C, then, according to Newton's Law of Cooling, the

muminat

Answer:

61°C

Step-by-step explanation:

Newton's Law of cooling gives the temperature -time relationship has:

T (t) = 20 + 75 е⁻(t/50)-------------------------------------------------------- (1)

where Time is in minutes (min) & Temperature in degree Celsius (°C)

During the first half hour, t = 30 mins

Substituting into (1)

T = 20 + 75 е⁻(30/50)

= 20 + 75(0.5488)

= 20 + 41.16

= 61.16°C

≈ 61°C

4 0

3 years ago