49r^2+21r=18

Solution for 49r^2+21r=18 equation:

49r^2+21r=18

We move all terms to the left:

49r^2+21r-(18)=0

a = 49; b = 21; c = -18;
Δ = b2-4ac
Δ = 212-4·49·(-18)
Δ = 3969
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3969}=63$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-63}{2*49}=\frac{-84}{98}
=-6/7
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+63}{2*49}=\frac{42}{98}
=3/7
$