Answer
Choice B; can be solved using Zero-Factor Property
Work Step by Step
The discriminant of a quadratic equation $ax^2+bx+c=0,$ is given by $\sqrt{b^2-4ac}$. Thus, the discriminant of the given equation, $ 25x^2+70x+49=0 ,$ is \begin{align*}\require{cancel} & \sqrt{70^2-4(25)(49)} \\&= \sqrt{4900-4900} \\&= \sqrt{0} \\&= 0 .\end{align*} Since the discriminant is zero, then the equation $ 25x^2+70x+49=0 $ has one rational number or $\text{ Choice b }$. Furthermore, since the coefficients of the given equation are integers and the discriminant is zero, then the given equation can be solved using the Zero-Factor Property.
