Simply multiply 3162 times 10 to find that 31620 is the answer.
If its 21 inches then rounding to the nearest who should be 21 inches
This gives you three simultaneous equations:
6 = a + c
7 = 4a + c
1 = c
<u>c = 1
</u><u /><u />
If c =1,
6 = a + 1
<u>a = 5
</u><u /><u />
This doesn't work in the second equation, so the quadratic that goes through these points is not in the form y = ax^2 + bx + c
Was there supposed to be a b in the equation?