Bonsoir,
a) V8 - 5V2 + V12
V(2^2 x 2) - 5V2 + V(3 x 2^2)
2V2 - 5V2 + 2V3
-3V2 + 2V3
b) V18 - 6V72 + 2V50
V(2 x 3^2) - 6V(2^2 x 2 x 3^2) + 2V(2 x 5^2)
3V2 - 36V2 +10V2
- 23V2
c) 3V5/2 x V12/V15
3V5 / V(3 x 5) x V(2^2 x 3)/2
3/V3 x 2V3/2
3V3/V3 x 2/2 = 3
d) (V3)^2 - (2V2/3)^2
3 - 8/9
27/9 - 8/9 = 19/9