How to solve quadratic equations with the coefficient not equal to 1?

Which coefficient? There are multiple, as the general formula of a quadratic equation is .
There are a few ways, and if you can factorise by inspection that works, however the most effective way of solving equations that aren't obvious is to plug it into the quadratic formula:

Idon’t understand what you’re asking..

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post