X is the number,
which when squared
X²
and added to 12
12+X²
becomes seven times its
value
7X
So these must be equal:
12+X² = 7X
X²-7X+12 = 0
(X-3)(X-4) = 0
X-3=0; X-4=0
X=3; X=4
Checking 3 in the words, not the equation:
3 is the number, which when squared, giving 9,
and added to 12, giving 21, becomes seven times its
value, 3. That checks because 7×3 is indeed 21.
So 3 checks.
Checking 4:
4 is the number, which when squared, gives 16,
and added to 12, giving 28, becomes seven times its
value, 4. That checks because 7×4 is indeed 28.
So 4 also checks.
So there are two solutions, 3 and 4.
Edwin
