Solving equations! Help me please

Question

a) 4x²-27=0

b) 4x²-8x-5=0

c)4x²-8x-12=0

d)4x²-9x-7=0

Instructions: For the following problems choose a method to solve them and explain why you would choose this method for each (factoring, square root property, completing the square, and the quadratic formula) Each method can only be chosen ONCE 

Answer 1

do the simplest one first:

4x²-27 = 0

x² = 27/4

x = (3√3) / 2 (Is this called the "square root property"?)

Next, which one can be factored? (b) and (c) are both easily factorable, but (d) is not---so try the quadratic formula:

4x²-9x-7=0

Formula is ( -b ± √(b2 - 4ac) ) / 2a

plug in the numbers:

b = -9

b2 = 81

4ac = -112

2a = 8

Do the math, and you'll see that this was a good choice for using the quadratic formula.

For (b) and (c), I think the choice between factoring and completing the square is a coin toss---try it both ways