Answer:
Step-by-step explanation:
Remark
The formula for this is
Heat = m * c * Δt
Givens
Heat = unknown
m = 200 grams
c = 4.184 Joules / grams oC
Δt = the change in temperature = 35.7 - 22.3 = 13.4
Solution
Heat = 200 * 4.184 * 13.4
Heat = 11213 Joules
Heat = 11.2 Kj
It's hard to get the correct number of sig digs because the 200 is not qualified in any way.
Part 2.
This can really puzzle you until you know that heat given up = the heat taken on. The heat taken on was 11.2 Kj. The Butane lighter must have given that heat on.
Heat of Combustion = Heat Given Up / Number grams burned.
Heat of Combustion = 11.2 Kj / 0.23 grams
Heat of Combustion = 48.8 Kj / gram
Answer:
The absoloute value is 2
Step-by-step explanation:
absoloute value is the places away from 0. -2 is 2 spots away from 0.
Answers:
- <u>24000 dollars</u> invested at 4%
- <u>18000 dollars</u> was invested at 7%
======================================================
Work Shown:
x = amount invested at 4%
If she invests x dollars at 4%, then the rest (42000-x) must be invested at the other rate of 7%
She earns 0.04x dollars from that first account and 0.07(42000-x) dollars from the second account
This means we have
0.04x+0.07(42000-x)
0.04x+0.07*42000-0.07x
0.04x+2940-0.07x
-0.03x+2940
This represents the total amount of money earned after 1 year.
We're told the amount earned in interest is $2220, so we can say,
-0.03x+2940 = 2220
-0.03x = 2220-2940
-0.03x = -720
x = -720/(-0.03)
x = 24000 dollars is the amount invested at 4%
42000-x = 42000-24000 = 18000 dollars was invested at 7%
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As a check, we can see that
18000+24000 = 42000
and also
0.04x = 0.04*24000 = 960 earned from the first account
0.07*18000 = 1260 earned from the second account
1260+960 = 2220 is the total interest earned from both accounts combined
This confirms our answers.
Answer:
{-2,10}
Step-by-step explanation:
x^2 - 8x = 20
Take the coefficient of x
-8
Divide by 2
-8/2 =-4
Square it
(-4)^2 =16
Add this to each side
x^2 - 8x+16 = 20+16
x^2 - 8x+16 = 36
The left hand side becomes( x + (-8/2) )^2
(x - 4)^2 = 36
Take the square root of each side
sqrt((x - 4)^2) =±sqrt( 36)
x-4 = ±6
Add 4 to each side
x-4+4 = 4±6
x = 4±6
x = 4+6 x = 4-6
x = 10 x = -2
