Answer: 5.4~
Explanation:
For the problem F(3) = 3x^2 +b, you have to first figure out what F(3) is and in this case it is 49, so now you have part of the question solved. Then you start working on the other side of the equation 3x^2 +b = 49, we don't know what x is so lets figure it out, by that you need to do 3x^2, the equals 9. So, so far we have the equation 49 = 9x +b. Now we need to get rid of the x on the 9, having a variable is considered multiplying so you need to divide 9 by 9, but remember what you do to one side you have to do to the other, so now you have to divide 49 by 9 and you get 5.444444444. Now the equation is b=5.4~ meaning that b is around 5.4, I hope this helps.