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# How many mL of a 0.10 M NaOH solution are needed to neutralize 15 mL of 0.20 M H3PO4? (answer)

Since there are 3 H's in H3PO4 and only 1 OH in NaOH that means you need three moles of NaOH for every mole of H3PO4. So Moles NaOH = 3x moles H3PO4 moles NaOH =0.1 moles/liter x L liters (L is our unknown) moles H3PO4 = 0.2 moles/liter x 0.015 liters so (0.1)L = 0.2(3)(0.015)...

# How would I find the cosine of a fraction of a variable? (answer)

You need to use trig identities. There is the double angle cos 2€ and 1/2 angle  identity cos 1/2€. If you can get your fraction to fit into one of these formulas you should be able to solve it from there. For example, if you have cos 1/4@ you could rewrite it as cos 2(1/8)@. The identity...

# f(x)=x^2/3 * (2-x) = x^2/3 * (2-x) (answer)

Robert's answer looks good.  If, however, the 3(2-x) is in the denominator, then try this:   f(x) = x^2 / (6-3x)   Use Chain Rule where a = x^2 and b = (6-3x)^-1   f'(x) = ab' + ba' f'(x) = (x^2)(-1)(-3)(6-3x)^-2 + 2x(6-3x)^-1 f'(x) = (3x^2)/(6-3x)^2...

# I am suppose to determine if the given equations are parallel, perpendicular, or neither. y= x+11; y= -x+2 (answer)

If two lines are parallel they have the same slope.  Since both of these equations are in slope intercept format, y=mx+b, it is easy to see the slope. It is the coefficient of the x, or m. What is the slope of the first line? It is the coefficient of x, which is 1. What is the slope...