The system of equations a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0 will have infinite solutions if:
1
\(\rm \frac{a_1}{a_2}=\frac{b_1}{b_2}\)
2
\(\rm \frac{a_1}{a_2}\ne\frac{b_1}{b_2}\)
3
\(\rm \frac{a_1}{a_2}=\frac{b_1}{b_2}=\frac{c_1}{c_2}\)
4
More than one of the above
5
None of the above