Question 293599
3x^2+3x=4
One approach is to make it equal to zero.
3x^2+3x-4=0
Another is complete the square
add 4
divide by 3

x^2+x=4/3
add (1/2)^2=1/4
x^2+x+1/4=4/3+1/4

(x+1/2)^2=16/12+3/12

(x+1/2)^2=19/12
I leave the rest for you
We could also use the quadratic formula.
*[invoke quadratic "x", 3, 3, -4 ]