D^2y/dx^2 = (dy dx)^2 true or false

Tomas is making trail mix using granola and walnuts. he can spend a total of $12 on the ingredients. he buys 3 pounds of granola that costs $2.00 per pound. the walnuts cost $6 per pound. he uses the equation to represent the total cost, where x represents the number of pounds of granola and y represents the number of pounds of walnuts. he solves the equation for y, the number of pounds of walnuts he can buy. answer- b tomas added 6 to both sides of the equation instead of subtracting 6. just took the test

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

Aphrase is shown read the phrase and give me the answer