1.7x(4x-21)=-1.7

Solution for 1.7x(4x-21)=-1.7 equation:

1.7x(4x-21)=-1.7

We move all terms to the left:

1.7x(4x-21)-(-1.7)=0

We add all the numbers together, and all the variables

1.7x(4x-21)+1.7=0

We multiply parentheses

4x^2-21x+1.7=0

a = 4; b = -21; c = +1.7;
Δ = b2-4ac
Δ = -212-4·4·1.7
Δ = 413.8
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-\sqrt{413.8}}{2*4}=\frac{21-\sqrt{413.8}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+\sqrt{413.8}}{2*4}=\frac{21+\sqrt{413.8}}{8}
$