1. VARIATION

2. 1 y varies directly with x.
If y = 6 when x = 3, find y when x = 2.
substitute y = 6 and x = 3 into the formula
solve to find k
put k = 2 into the formula y = kx
This is the formula connecting y and x.

3. 2 y varies directly with x.
If y = 15 when x = 2.5, find x when y = 3.
substitute y = 15 and x = 2.5 into the formula
solve to find k
put k = 6 into the formula y = kx
This is the formula connecting y and x.

4. 3 y varies directly with the square of x.
If y = 48 when x = 4, find x when y = 12.
substitute y = 48 and x = 4 into the formula
solve to find k
put k = 3 into the formula y = kx2
This is the formula connecting y and x.

5. 4 y varies inversely with x.
If y = 2 when x = 3, find y when x = 5.
substitute y = 2 and x = 3 into the formula
solve to find k
put k = 6 into the formula
This is the formula connecting y and x.

6. 5 y varies inversely with the square root of x.
If y = 6 when x = 4, find y when x = 36.
substitute y = 6 and x = 4 into the formula
solve to find k
put k = 12 into the formula
This is the formula connecting y and x.