42+7d=21(1/2d+2)

Solution for 42+7d=21(1/2d+2) equation:

42+7d=21(1/2d+2)

We move all terms to the left:

42+7d-(21(1/2d+2))=0


Domain of the equation: 2d+2))!=0

d∈R


We multiply all the terms by the denominator


7d*2d+42*2d+2))-(21(1+2))=0

We add all the numbers together, and all the variables

7d*2d+42*2d+2))-(213)=0

We add all the numbers together, and all the variables

7d*2d+42*2d=0

Wy multiply elements

14d^2+84d=0

a = 14; b = 84; c = 0;
Δ = b2-4ac
Δ = 842-4·14·0
Δ = 7056
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7056}=84$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(84)-84}{2*14}=\frac{-168}{28}
=-6
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(84)+84}{2*14}=\frac{0}{28}
=0
$