The discriminant of a quadratic expression [tex]\displaystyle{ ax^2+bx+c[/tex] is
[tex]\displaystyle{ D=b^2-4ac[/tex].
In the quadratic [tex]4x^2+7x-15[/tex], a=4, b=7, and c=-15.
Thus, [tex]\displaystyle{ D=b^2-4ac=7^2-4(4)(-15)=49+240=289>0[/tex].
The discriminant is positive, this means that the equation has 2 real solutions.
Answer: 2
