mathcalc
posted by joe on .
show that 1(x/2) is the tangent line approximation to 1/sq rt(1+x) near x=0
i know the formula for apprx. is y = f(a)+f'(a)(xa) but i don't understand how to work backwards to get this.

If f(x) is approximated by the tangent line y(x) near x = 0, then that means that:
f(0) = y(0)
f'(0) = y'(0)