Answer:
-7-√15
Step-by-step explanation:
First move the constant to the right hand side and change it's sign
x^2+14x=-34
Then add (14/2)^2 or 7^2 to both sides
x^2+14x+49=-34+49
Then factor the expression
(x+7)^2=-34+49
Then solve (x+7)^2=15
You should get:
x=-√15-7
or
x=√15-7
For part (a) the answer is 400 grams for part (b) 198.63 grams and for part (c) 20 years.
<h3>What is exponential decay?</h3>
During exponential decay, a quantity falls slowly at first before rapidly decreasing. The exponential decay formula is used to calculate population decline and can also be used to calculate half-life.
We have an equation for radioactive decay:

a) Plug t = 0

m(0) = 400 grams
b) plug t = 20 years

After solving:
m(20) = 198.63 grams
c) Plug m(t) = m(0)/2 = 400/2 = 200 grams

x = 19.80 years ≈ 20 years
Thus, for part (a) the answer is 400 grams for part (b) 198.63 grams and for part (c) 20 years.
Learn more about the exponential decay here:
brainly.com/question/14355665
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Answer:
Interest will amount to $142.58
Total amount Levi will have to pay back at the end of 6 months=$7271.58
Step-by-step explanation:
Simple interest=principal×rate×time
Principal=$7129
Rate=4%=0.04
Time=6 month=0.5 year
Simple interest=principal×rate×time
=$7129×0.04×0.5
=$142.58
Interest will amount to $142.58
Total amount Levi will have to pay back at the end of 6 months
=principal + total interest
=$7129+$142.58
=$7271.58