does using toothpast with baking soda make my teeth whiter than toothpaste without baking soda? What’s the Independent variable and what’s the dependent variable, and also constant.

Charge is distributed along the entire x-axis with uniform density λ. how much work does the electric field of this charge distribution do on an electron that moves along the y-axis from y = a to y = b? (use the following as necessary: a, b, ε0, λ, and q for the charge on an electron.)