domain (c^2+4c)/(c^2-4)*(c-2)/(3c+12)
1) Let's evaluate the domain of c2 + 4cc2 -4·c -23c + 12
For the expression c2 + 4cc2 -4 to exist, you must check: c2 -4 ≠ 0
For the expression c -23c + 12 to exist, you must check: 3c + 12 ≠ 0
2) Let's solve in ℝ: c2 -4 ≠ 0
The two numbers whose square is 4 are -2 and 2
Solution found: c ∈ ℝ \ { -2, 2 }
3) Let's solve in ℝ: 3c + 12 ≠ 0
ⓘ We subtract 12 from both sides
3c ≠ -12
ⓘ Both sides are divided by 3
c ≠ -123
ⓘ We simplify the fraction by dividing the numerator and the denominator by 3, their greatest common divisor: -123 = -4
Solution found: c ≠ -4
Let's build the table of the different terms to determine the global solution:
c-∞ -4 -2 2 +∞
c2 -4 ≠ 0✅✅✅❌✅❌✅
3c + 12 ≠ 0✅❌✅✅✅✅✅
Domain of definition: ✅❌✅❌✅❌✅
▶Domain of definition:   c ∈ ℝ \ { -4, -2, 2 }