7m^2-42m-49=0

Solution for 7m^2-42m-49=0 equation:

7m^2-42m-49=0

a = 7; b = -42; c = -49;
Δ = b2-4ac
Δ = -422-4·7·(-49)
Δ = 3136
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3136}=56$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-42)-56}{2*7}=\frac{-14}{14}
=-1
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-42)+56}{2*7}=\frac{98}{14}
=7
$