No, it is not. To be correct, the expression requires parenthesis, which are missing.
4 squared minus 2 squared equals 12
The answer is 4 squared minus 2 squared as 4 squared is 16 minus 2 squared, which is 4, gives you 12 as an answer.
x + 1
None of the graphs that I can see!
By factoring I get x-3 divided by x+3
x - 3
7x + 8
4x + 20
x - 5
2b - 1
The question contains an expression but not an equation. You cannot solve an expression.
It simplifies to 5a+4 !
2x squared minus 4
n squared minus n
Multiply both sides by sin(1-cos) and you lose the denominators and get (sin squared) minus 1+cos times 1-cos. Then multiply out (i.e. expand) 1+cos times 1-cos, which will of course give the difference of two squares: 1 - (cos squared). (because the cross terms cancel out.) (This is diff of 2 squares because 1 is the square of 1.) And so you get (sin squared) - (1 - (cos squared)) = (sin squared) + (cos squared) - 1. Then from basic trig we know that (sin squared) + (cos squared) = 1, so this is 0.
82 / 2 = 64/2 = 32 - 8 = 24 - 3 = 21