Pauline invested $10000 at two different rates,4% and6%.If his interest income was $470,how much did he invest in each rate?
1 answer:
<h2>Steps</h2>
So for this, I will be doing a system of equations. Let x = money invested at 4% and y = money invested at 6%. We know that x and y will total up to 10k since that's how much he initially invested, so that'll be one of our equations.
Our other equation will represent the total balance he has after investing. We know that x's interest is 4% (since the money is <em>increasing,</em> this would translate to 1.04 in decimal form) and y's interest is 6% (aka 1.06 in decimal form since its <em>increasing</em>) and that the total balance is 10470 (initial balance + interest income).
Using all this info, these are our two equations:
For this, I will be using the substitution method. For the first equation, subtract y on both sides of the equation:
Next, substitute x in the second equation for (10000 - y) and solve for y as such:
Now that we have the value of y, substitute it into either equation to solve for x:
In short:
- $6,500 was invested in the 4% rate
- $3,500 was invested in the 6% rate
You might be interested in
Answer:
(i) (x +4)^3 = x^3 +12x^2 +48x +64
(ii) (2m +1)^3 = 8m^3 +12m^2 +6m +1
(iii) (a -2b)^3 = a^3 -6a^2b +12ab^2 -8b^3
Step-by-step explanation:
Powers of a binomial have a pattern. The coefficients of the terms of the expanded product are the numbers in the corresponding row of Pascal's Triangle. Here, you want the 3rd power, so the coefficients of interest are ...
1, 3, 3, 1
The pattern is ...
(a +b)^2 = a^2 +2ab +b^2
(a +b)^3 = a^3 +3a^2b +3ab^2 +b^3
The total of powers of the variable is equal to the exponent of the binomial. The powers of the first variable decrease to 0 while the powers of the second variable increase from zero.
When 'a' or 'b' is something with a coefficient, that whole term is raised to the appropriate power.
__
i) (x+4)^3 = x^3 +3·4x^2 +3·4^2x +4^3
(x +4)^3 = x^3 +12x^2 +48x +64
__
ii) (2m +1)^3 = (2m)^3 +3·1·(2m)^2 +3·1^2·(2m) +1^3
(2m +1)^3 = 8m^3 +12m^2 +6m +1
__
iii) (a -2b)^3 = a^3 +3·a^2·(-2b) +3·a·(-2b)^2 +(-2b)^3
(a -2b)^3 = a^3 -6a^2b +12ab^2 -8b^3
_____
<em>Additional comment on Pascal's triangle</em>
The numbers in each row are the sums of the two numbers immediately above. For binomial expansion, you're only interested in the contents of a row. The "patterns" shown in the attachment are an extra added attraction, not particularly relevant to binomial expansion.
