21m^2+10m+8=7

Solution for 21m^2+10m+8=7 equation:

21m^2+10m+8=7

We move all terms to the left:

21m^2+10m+8-(7)=0

We add all the numbers together, and all the variables

21m^2+10m+1=0

a = 21; b = 10; c = +1;
Δ = b2-4ac
Δ = 102-4·21·1
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(10)-4}{2*21}=\frac{-14}{42}
=-1/3
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(10)+4}{2*21}=\frac{-6}{42}
=-1/7
$