Question

Which equation shows the quadratic formula used correctly to solve 5x2 + 3x – 4 = 0 for x?

Answer 1

Answer:

The equation $x=\frac{-3\pm \sqrt{(3)^2-4(5)(-4)}}{2(5)}$ shows the quadratic formula used correctly to solve the given quadratic equation.

Step-by-step explanation:

The given equation is

$5x^2+3x-4=0$            .... (1)

If a quadratic equation is defined as

$ax^2+bx+c=0$           ..... (2)

then the quadratic formula is

$x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

From equation (1) and (2), we get

$a=5,b=3,c=-4$

Using quadratic formula we get

$x=\frac{-3\pm \sqrt{(3)^2-4(5)(-4)}}{2(5)}$

Therefore the equation $x=\frac{-3\pm \sqrt{(3)^2-4(5)(-4)}}{2(5)}$ shows the quadratic formula used correctly to solve the given quadratic equation.

Answer 2

5x^2+3x-4=0 
x^2+3x/5-4/5=0 
x^2+3x/5=4/5 
x^2+3x/5+9/100=89/100 
(x+3/10)^2=89/100 
x+3/10=±(√89)/10 
x=-3/10±√89/100 
x=-3±(√89/10)