Answer: A; 6.3%
Step-by-step explanation:
Problem 1
For the first problem, we first want to find y so that we can plug it into the expression.
We can use elimination method for the system of equations to solve.
3x+3y=21
3x-y=5
We subtract both equations to eliminate x.
4y=16 [divide both sides by 4]
y=4
Now that we know y, we can plug it into the expression.
[divide]
[subtract]
We know that the answer is A.
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Problem 2
For the second problem, we need to know how to calculate percent error. The formula for precent error is 
. We know that the exact value is 80 because the buyer was supposed to given 80. 75 is the measured value because that was what the buyer was given.
[subtract]
[solve absolue value]
[divide]
[multiply]
Since the problem said to round to one decimal place, we know that the answer is 6.3%.
Answer:
Y=K×X...... equation
When,Y=8 and X=-5
To find the constant (K)
we substitute for K in the equation
8=K×-5
8=-5K divide both sides by -5
8÷-5=-5K÷-5
K=-1.6
Answer:
y = 4000/x²
Step-by-step explanation:
The volume of the building is expressed as;
V = x²y where;
x is the length and width of the base.
y is the height of the building
Given
Volume V = 4000m³
Substitute the given volume into the equation as shown;
4000 = x²y
Make y the subject of the formula by dividing both sides by x²
4000/x² = x²y/x²
4000/x² = y
Rearrange
y = 4000/x²
Hence equation for y, the height of the building, in terms of x, the length and width of the base is expressed as y = 4000/x²
Answer:
x-5<21
Step-by-step explanation:
