Please answer 7/10k=21 find x ill give you brainliest
1 answer:
You might be interested in
<h3>Answers:</h3>
- 48 seconds
- 3624 feet
========================================================
Explanation:
x = number of seconds that elapse
y = altitude (aka height) of the plane
The equation for plane A is
y = 20.25x+2652
because it starts off at 2652 ft in the air, and then adds on 20.25 feet per second which is what the 20.25x describes
The equation for plane B is
y = 75.5x
The y intercept is zero because plane B starts on the ground, aka height 0.
------------------
The system of equations is
If we want to know when they'll reach the same height (y), then we can set the two right hand sides equal to each other and solve for x.
75.5x = 20.25x+2652
75.5x-20.25x = 2652
55.25x = 2652
x = (2652)/(55.25)
x = 48
The two planes reach the same altitude at exactly <u>48 seconds</u>
That altitude is <u>3624 feet</u> because
- y = 20.25*x + 2652 = 20.25*48+2652 = 3624
- y = 75.5*x = 75.5*48 = 3624
Notice I plugged x = 48 into each equation and I got the same y value of y = 3624. This helps confirm the answers.
We can make a proportion to represent the woods used. On the top is cedar, and on the bottom is the redwood. On the left is what was used the first time, on the right is the current problem.
Before making the proportion, let's do a preliminary step and write all the fractions as improper fractions. We do this because we can't directly multiply or divide mixed numbers, but we can with fractions.
<-- Multiply denominator times whole number and add the leftover fraction.
Now we set up the proportion. We solve it by cross multiplying.
It may seem right to simplify the right side, but let's leave it alone. We divide both sides by 19/2.
Dividing by a fraction means multiplying by its reciprocal. Thus,
Here's where not simplifying really pays off. We can simplify NOW and the terms go away more easily. The 19s go away and simplify to 1, and the 2 and 4 simplify to 1 and 2. All this happens by dividing out common numbers.
Now we multiply all the tops and all the bottoms.
R = 23 * 1 * 1 / 3 * 2 * 1
R = 23 / 6
While R is 23/6, we need to make it a mixed number. The way we made mixed numbers as improper fractions happens here, except in reverse.
23 ÷ 6 = 3 with a remainder of 5, as 3 × 6 + 5 = 23. Thus, .
As a result, feet of redwood is needed.