急! F5 Graphs of Functions 3q6

11.
(a)
y = 2^x ...... [1]
y = 0.7 ...... [2]

[1] = [2] :
2^x = 0.7
Hence, 2^x - 0.7 = 0
but given that : 2^x + k = 0
Hence, k = -0.7

y = 2^x and y = 0.7 intersect at x = -0.5
Hence, roots of the equation : x = -0.5


(b)
y = 2^x ...... [1]
y = 3.5 ...... [3]

[1] = [3] :
2^x = 3.5
Hence, 2^x - 3.5 = 0
but given that : 2^x + k = 0
Hence, k = -3.5

y = 2^x and y = 3.5 intersect at x = 1.8
Hence, roots of the equation : x = 1.8