Hence find the value of $$$y$$$ such that $$$\left|2^{1-y}-5\right|=\left|2^{-y}+6\right|$$$. Give your answer correct to 3 significant figures. ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................

Mathematics

IGCSE&ALevel

CAIE

Exam No：9709_w20_qp_23 Year：2020 Question No：4(b)

Answer:

Apply logarithms and use power law for $2^{-y}=k$ where $k>0$ from (a)
Obtain $-3.46$

2.2.3 use logarithms to solve equations and inequalities in which the unknown appears in indices