Nine and a half times.
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you can put it fully nine times. You reach 18 like this. But you have 1 more to go until 19! So, just cut the 2 in half to get 1, and put that in!
If you factor the equation you can see what the solutions are. Two factor a quadratic of the form ax^2+bx+c, find two values which satisfy two conditions...
jk=ac=-15 and j+k=b=-2 so j and k must be -5 and 3 so the factors are:
(x-5)(x+3)
So the other solution is x=5
13/32=0.40625 that would be the answer to the problem
From greatest to least it would be
5.43; 5.340; 5.249; 5.209