completing the square

Step-by-step explanation:

5x² - 15x - 4 = 0

Add 4 to both sides.

5x² - 15x = 4

The coefficient of 5x² is 5, divide both sides by 5.

x² - 3x = 4/5

The coefficient of -3x is -3. Let b=-3.

Then we need to add (b/2)^2=9/4 to both sides to complete the square.

Add 9/4 to both sides.

x² - 3x + 9/4 = 61/20

Factor left side.

(x-3/2)² = 61/20

Take square root of both sides.

x-3/2 = ± √(61/20)

Add 3/2 to both sides.

x = 3/2 ± √(61/20)

answer

a,b, and d

explanation

a reflection angle is more than

but less than;

an angle that measures

is a reflex angle.(true)

an angle that measures less than

is acute.(true)

provided we are considering angles greater or equal to zero.

an acute angle lies in the range.

an obtuse angle is less than 180° but more than 90°

an angle that measures 300° is obtuse (false)

an angle that measures 65° is an acute angle.(true)