They always try to trick you with this. Remember anything 5 or above would round up, anything 4 and under would round down. So look for the tenth place. that's the 9. The number to the right is 8 which is greater than 5. That means round up. You can't round it to 0.1 because that takes it back down. So you just move it over. The answer is 1.0.
You obviously don't mind using "technology" (Brainly) to answer these questions. A graphing calculator can do quadratic regression on the sequence and tell you its formula.
If you want to do it by hand, you can write the equation .. y = ax^2 +bx +c and substitute three of the given points. Then solve the resulting three linear equations for a, b, and c. .. 4 = a +b +c .. 7 = 4a +2b +c .. 12 = 9a +3b +c
Subtracting the first equation from the other two reduces this to .. 3 = 3a +b .. 8 = 8a +2b The latter can be divided by 2, so reduces to .. 4 = 4a +b Subtracting the first of the reduced equations from this, you have .. 1 = a so .. 3 = 3*1 +b .. 0 = b and .. 4 = a + b + c = 1 + 0 + c .. 3 = c
And your equation is .. y = x^2 +3 . . . . . . as shown previously