Answer: 
Step-by-step explanation:
Observe in the figure given in the exercise that four right triangles are formed.
In this case you can use the following Trigonometric Identity to solve this exercise:
From the figure you can identify that:

Then, you can substitute values:

The next step is to solve for DE in order to find its value. This is:

Finally, rounding the result to the nearest tenth, you get that this is:

8<-5x+20 is one possible answer. it depends on how they are writing it. you need to do the distributed property.
Answer:

Step-by-step explanation:
Quadratic function-
It is a function that can be represented by an equation of the form
, where
In a quadratic function, the greatest power of the variable is 2.
As in the first option the highest power is 3, so it is not a quadratic function.
Even though the power of x is 2 in the third option, but as it is in the denominator, so the overall power of x becomes -2. Hence it is not a quadratic function.
As the coefficient of
is 0 in case of fourth option, so it is not a quadratic function.
Equation in option 2 satisfies all the conditions of quadratic function, hence it is the quadratic function.
Answer:
He must invest R297 521 today.
Step-by-step explanation:
The compound interest formula is given by:

Where A(t) is the amount of money after t years, P is the principal(the initial sum of money), r is the interest rate(as a decimal value), n is the number of times that interest is compounded per year and t is the time in years for which the money is invested or borrowed.
Banabas must pay his ex-wife an amount of R350 000 in two years’ time.
This means that 
Interest rate of 8.15% per annum compounded monthly:
This means that
.
Amount he must invest today:
This is P. So




He must invest R297 521 today.