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2 years ago

Find x if f(x)=2x+7 and f(x)=-1

Mathematics

1 answer:

Natalija [7]2 years ago

7 0

Answer:

$x = -4$

Step-by-step explanation:

$~~~~~~f(x) = -1\\\\\implies 2x +7 = -1\\\\\implies 2x = -1 - 7\\\\\implies 2x = -8 \\\\\implies x = -\dfrac 82 \\\\\implies x = -4$

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Find the value of a and b<br><br> a^2 + b^2 = 400

Oliga [24]

Answer:

Step-by-step explanation:

a^2+b^2=400

a^2=400-b^2

a=sqrt(400-b^2) & -sqrt(400-b^2)

-----------------------------------------------

b^2=400-a^2

b=sqrt(400-a^2) & -sqrt(400-a^2)

7 0

4 years ago

Read 2 more answers

A motorboat takes 5 hours to travel 100 kilometers going upstream. The return trip takes

tatuchka [14]

Step-by-step explanation:

Let's say b is the rate of the boat in still water, and c is the rate of the current.

Distance = rate × time

Going upstream:

100 = (b − c) (5)

20 = b − c

Going downstream:

100 = (b + c) (2)

50 = b + c

Solve the system of equations using substitution or elimination. Using elimination, add the equations together:

70 = 2b

b = 35

c = 15

The boat's speed is 35 km/h, and the current's speed is 15 km/h.

8 0

3 years ago

If y varies inversely as x and y=32 when x=3, find x when y=15

deff fn [24]

Y=kx, k is not equal to 0
when y=32,x=3, 32=3k
k=32/3
so y=32/3*x
when y=15, 15=32/3*x
x=45/32

5 0

3 years ago

A golf ball is hit in not the air represented by the equation y= -3x^2+18x+45. The maximum height the ball will reach is____ fee

Temka [501]

Answer:

72 ft

Step-by-step explanation:

Here, we want to get the maximum height the ball will reach

the maximum height the ball will reach is equal to the y-coordinate of the vertex of the equation

So we need firstly, the vertex of the given quadratic equation

The vertex can be obtained by the use of plot of the graph

By doing this, we have it that the vertex is at the point (3,72)

Thus, we can conclude that the maximum height the ball can reach is 72 ft

3 0

3 years ago

Jon recently drove to visit his parents who live 280 miles away. On his way there his average speed was 9 miles per hour faster

Luba_88 [7]

Answer:

11 mph and 20 mph

Step-by-step explanation:

Represent his average speed going by r1 and his average speed returning by r2. We know that r1 = r2 + 9.

Recall that distance = rate times time, so time = distance / rate.

Time spent going was (280 mi) / r1, or (280 mi) / (r2 + 9 mph).

Time spend returning was (280 mi) / r2.

The total time was 14 hrs, so (280 mi) / (r2 + 9 mph) + (280 mi) / r2 = 14 hrs

Note that there is only one variable here: r2. Find r2, and then from r2, find r1:

Dividing all 3 terms by 14 hrs yields:

20 20

---------- + ----------- = 1

r2 + 9 r2

The LCD here is r2(r2 + 9). Thus, we have:

20r2 (r2 + 9)(r2)

------------------- = 1 or ------------------

(r2 + 9)(r2) (r2 + 9)(r2)

Then 20(r2) = (r2)^2 + 9(r2). This is reducible by dividing all terms by r2:

20 = r2 + 9, or 11 = r2. Then r1 = 11 + 9, or 20.

The two rates were 11 mph and 20 mph.

8 0

4 years ago