Question

GCSE MATHS PLEASE HELP

Answer 1

Answer:

A) y = 16/(x^2), B) 4/5

Step-by-step explanation:

For A, we can plug in some of the table values to check it. I will try 2 and 3

2. 4 = 16 / (2^2)

    16/4 = 4

3. 16/9 = 16 / (3^2)

   16/9 = 16/9

B) We can just input y into the formula 25 = 16 / (x^2)

This leaves us with +-4/5

Answer 2

Answer:

see explanation

Step-by-step explanation:

(a)

given y varies inversely as x² then the equation relating them is

y = $\frac{k}{x^2}$ ← k is the constant of variation

to find k substitute any ordered pair from the table into the equation

using (2, 4 ) , then

4 = $\frac{k}{2^2}$ = $\frac{k}{4}$ ( multiply both sides by 4 )

16 = k

y = $\frac{16}{x^2}$ ← equation of variation

(b)

when y = 25 , then

25 = $\frac{16}{x^2}$ ( multiply both sides by x² )

25x² = 16 ( divide both sides by 25 )

x² = $\frac{16}{25}$ ( take the square root of both sides )

x = ± $\sqrt{\frac{16}{25} }$ = ± $\frac{4}{5}$

the positive value of x is x = $\frac{4}{5}$