Answer:
A) y = x^2 -1
B) -y = 2x^2 +1 We multiply B) by -1
B) y = -2x^2 -1
We can then say x^2 -1 = -2x^2 -1
3 x^2 = 0
x = 0
************* Double-Check: ******************
Equation A) y = -1 and
Equation B) y = -1
Step-by-step explanation:
18 kg of 15% copper and 72 kg of 60% copper should be combined by the metalworker to create 90 kg of 51% copper alloy.
<u>Step-by-step explanation:</u>
Let x = kg of 15% copper alloy
Let y = kg of 60% copper alloy
Since we need to create 90 kg of alloy we know:
x + y = 90
51% of 90 kg = 45.9 kg of copper
So we're interested in creating 45.9 kg of copper
We need some amount of 15% copper and some amount of 60% copper to create 45.9 kg of copper:
0.15x + 0.60y = 45.9
but
x + y = 90
x= 90 - y
substituting that value in for x
0.15(90 - y) + 0.60y = 45.9
13.5 - 0.15y + 0.60y = 45.9
0.45y = 32.4
y = 72
Substituting this y value to solve for x gives:
x + y = 90
x= 90-72
x=18
Therefore, in order to create 90kg of 51% alloy, we'd need 18 kg of 15% copper and 72 kg of 60% copper.
Because they will give you the same answers lol
1 true and false question = 1 / 2 chances
2 multiple choice question = 2/8
1/2 + 2/8 =
4/8 + 2/8 = 6/8.
6/8 = 3/4
you have a 75% chance of getting all 3 answers correct and getting a 100% on the quiz
hope this helps :D
