12−6=7+9
12
x
−
6
=
7
x
+
9

d. 9

step-by-step explanation:

54/12 = 4.5

sf = 4.5

so x = 2 · 4.5 = 9

explanation:

infrared radiation has wavelength in the range between 700 nm and 1 mm. lets' convert these values into scientific notation, keeping in mind that:

let's start from the lower value, we have:

(we moved the dot two places to the left, so we increased the exponent by 2 units, from -9 to -7)

the higher value is:

so, the range of wavelength of infrared radiation is:

b. b < 1 might be the correct answer