3k(-k+7)=36

Solution for 3k(-k+7)=36 equation:

3k(-k+7)=36

We move all terms to the left:

3k(-k+7)-(36)=0

We add all the numbers together, and all the variables

3k(-1k+7)-36=0

We multiply parentheses

-3k^2+21k-36=0

a = -3; b = 21; c = -36;
Δ = b2-4ac
Δ = 212-4·(-3)·(-36)
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-3}{2*-3}=\frac{-24}{-6}
=+4
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+3}{2*-3}=\frac{-18}{-6}
=+3
$