Mrs smith invests £30,000 (some in a 5% account, some in an 8% account). After the year shes earned £2100. How much did she put in each account? PLEASE HELP!!

She deposited £10,000 in the 5% yield account and deposited £20,000 in the 8% yield account

Step-by-step explanation:

Let the amount she put in each account be £x and £y respectively

Total amount deposited is ;

x + y = 30,000 ••••••(i)

Now, let’s look at the earnings:

in the £x , amount earned would be;

5/100 * x = 5x/100

For the £y, amount earned would be;

8/100 * y = 8y/100

Adding both gives the total which is £2,1000

5x/100 + 8y/100 = 2,100

Multiply through by 100

5x + 8y = 210,000 ••••••••(ii)

From the first equation, we know that

x = 30,000 -y

Let’s put this into the second

5(30,000-y) + 8y = 210,000

150,000-5y + 8y = 210,000

3y = 210,000 -150,0000

3y = 60,000

y = 60,000/3

y = £20,000

So mathematically;

x = 30,000-y

x = 30,000 -20,000

x = £10,000

this question relies purely on our observation of the graph and a knowledge of the behaviour of a graph of a hyperbola.

now, what we should realise is that there are two asymptotes - one at x = 0 and one at y = 0. what this means is that the graph will gradually approach, but never touch, these two lines. so, as x becomes more positive (ie. 'a very large positive number'), it will get closer to the line y = 0 (ie. the x-axis) - which means that the value of f(x) will gradually become smaller and closer to 0 - but will never reach it.

we can also observe this from the right half of the graph, where the graph gradually lowers closer and closer to the x-axis as x increases. what is important to note however is that it will never actually touch the x-axis (ie. f(x) will not equal 0) since there is an asymptote there. given this, we can see that option d, f(x) is a very small positive number, would be correct.