200=1.75t^2

Solution for 200=1.75t^2 equation:

200=1.75t^2

We move all terms to the left:

200-(1.75t^2)=0

We get rid of parentheses

-1.75t^2+200=0

a = -1.75; b = 0; c = +200;
Δ = b2-4ac
Δ = 02-4·(-1.75)·200
Δ = 1400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1400}=\sqrt{100*14}=\sqrt{100}*\sqrt{14}=10\sqrt{14}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-10\sqrt{14}}{2*-1.75}=\frac{0-10\sqrt{14}}{-3.5}
=-\frac{10\sqrt{14}}{-3.5}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+10\sqrt{14}}{2*-1.75}=\frac{0+10\sqrt{14}}{-3.5}
=\frac{10\sqrt{14}}{-3.5}
$