im not surenhow to do this

factorise 4(x+3)+x(x+3)

 

Think about this:

 

4A+XA

This is 4 lots of A plus X lots of A

so when you factored it you will have  A(4+X)     or    (4+X) *A

 

WELL

your question is the same. 

 

4(x+3)+x(x+3)

This is 4 lots of (x+3)  plus  x lots of (x+3)   

when you put it together you have  (4+x) lots of (x+3)  which is just  (4+x)(x+3)

this woul normally be reorganised as 

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