Question

Can anyone please help me with the following? I can't remember from my high school algebra...
Square root of (1+9x^2)
I can't remember how to simplify the term to be able to square root it easily, because I know you may not say 1+9x^2 = (1+3x)^2

Answer 1

\(\large \sqrt{1+9x^2}\)

Answer 2

trying to see, if i understood the question correctly :)

Answer 3

we cant simplify it right any further, right ?

Answer 4

btw, below statement doesn't look corrct :-

\(1+9x^2 = (1+3x)^2 \)

Answer 5

Yes, that's exactly what it looks like :)

Answer 6

And yes, I assumed I may not do that assumption :)

Answer 7

okay :) lets see if below is correct or not :-

\(1+9x^2=(1+3x)^2\)

Answer 8

how can we **know** if above equation we have put is correct or not ?
shall we expand the right side and see ? :)

Answer 9

do u remember this formula : \((a+b)^2 = a^2+b^2+2ab\)

Answer 10

Yes, then we get \[1 + 6x + 9x^2?\]

Answer 11

yup :) is it fine to conclude

\(1+9x^2 \ne (1+3x)^2\)

?

Answer 12

Definitely :) Is there then no way to simplify \[1 + 9x^2\]? :(

Answer 13

\(\sqrt{1+9x^2}\)

i don't think we can do anything much here. it looks fully simplified to me.... :|

Answer 14

Awww, dangit. Thank so much anyways :)

Answer 15

may i knw the context of this q, so we can discuss further... if u want ? :)

Answer 16

Sure! It was the following:
Find the surface area generated when the graph of the equation \[f(x)=x^3\] is revolved around the x-axis at points A(1,1) and B(2,8)

Answer 17

Ahh calculus !

Answer 18

then im sure u knw pretty well wat u doing lol ^_^

Answer 19

And when I differentiated \[x^3\] I got \[3x^2\] and in my formula for getting the surface area, i had to solve \[\sqrt{1 +(3x^2)^2}\]Maybe I missed something???

Answer 20

Hahaha thanks ^_^