Let $7x^2 + 5x = h.$ What value of $h$ will give us exactly one solution for $x$?
7x^2 + 5x = h
7x^2 + 5x - h = 0
We will have one solution when the discriminant = 0
So
5^2 - 4(7)(-h) = 0
25 + 28h = 0
25 = - 28h
-25/28 = h
This graph shows that this is true :
https://www.desmos.com/calculator/jbpjhjdgt4
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