For what value of $h$ does the quadratic $7x^2 + 5x = h + 6x^2 - 3x$ have exactly one real solution in $x$?
7x^2 + 5x = h + 6x^2 - 3x
7x2 – 6x2 + 5x + 3x – h = 0
Combine units. x2 + 8x – h = 0
This is in the form ax2 + bx + c
To have only one solution means
that the expression is a square.
For it to be a square, then b2 – 4ac has to equal zero.
82 – (4)(1)(–h) = 0
64 + 4h = 0
4h = –64
h = –16
Check Answer
Substitute –16 into the
quadratic equation. x2 + 8x –(–16)
x2 + 8x + 16
Will this factor? Yes. (x + 4)(x + 4)
.