Please can someone help me? In the Edexcel C4 Book, Exercise 6F Q3a I can't seem to understand why we have to substitute u^2 = x+4 instead of u=x+4 Any help would be great thanks
You can substitute either u^2 = x+4 or u= x+4. I did this exercise last night using u= x+4 and it worked. However for some questions such as Q3 c, the substitution they offer is generally the best and easiest option to integrate.
You can substitute either u^2 = x+4 or u= x+4. I did this exercise last night using u= x+4 and it worked. However for some questions such as Q3 c, the substitution they offer is generally the best and easiest option to integrate.
Oh I see, thank you. I must've made a mistake because I used u=x+4 but didn't get the right answer.