Given,

3x² + 10x + 8

Now first find the numbers whose-

Sum = 10 and

Product = 3 × 8 = 24

Required numbers are 6 and 4,

So we get;

3x² + 10x + 8

= 3x² + 6x + 4x + 8

= 3x(x + 2) + 4(x + 2)

= (x + 2)(3x + 4)