Evaluate the expression 3.14(a2 + ab) when a = 3 and b = 4. (input decimals only, such as 12.71, as the answer.)

12. the amount of money in a bank account decreased by 21.5% over the last year. if the amount of money at the beginning of the year is represented by ‘n', write 3 equivalent expressions to represent the amount of money in the bank account after the decrease?

X2 + y 2 = 36 x + y = 6 solve the system of equations.

Asap! i'm not good math and i'm lost.