What is the negative x-intercept of the graph of the quadratic function f(x) = 5x2 + 4x - 1? a) - 7 5 b) - 2 5 c) - 1 5 eliminate d) -1

D

Step-by-step explanation:

The quadratic formula is

.

It is important because while some quadratics are factorable and can be solved not all are. The formula will solve all quadratic equations and can also give both real and imaginary solutions.  Using the formula will require less work than finding the factors if factorable. We will substitute a=5, b=4 and c=-1.

We will now simplify and solve.

x=-1 and x=0.2

5=812a+9+3

step 1: simplify both sides of the equation.

5=812a+9+3

5=(812a)+(9+3)(combine like terms)

5=812a+12

5=812a+12

step 2: flip the equation.

812a+12=5

step 3: subtract 12 from both sides.

812a+12−12=5−12

812a=−7

step 4: divide both sides by 812.

812a /812 = -7/812

a= -1/116

so the answer is

a=   -1/116