How do I solve this, please?

Gotta factorise it:

( 2x + 5 ) ( x - 4 )

So

X = -2.5 & X = 4

This is how we solve Quadratic Equation:

2x^2-3x-20=0

2x^2-8x+5x-20=0

2x(x-4)+5(x-4)=0

(2x+5)(x-4)=0

x=-5/2,4

(2x+5)(x-4)=0 so x=-5/2 or x=4

2x squared -3x -20=0 +20

2x squared -3x = 20 i then used elimination

x=1

2-3=-1

x=2

8-6= 2

x=3

18-9=9

x=4

32-12=20

so thats your answer

x=4

2x^2-3x-20=0

(2x+5)(x-4)

2x+5=0

-5+5=0

2x=-5

x=-2.5 or -5/2

Now for the x-4=0

4-4=0

x=4

So the answers are x=-2.5 or -5/2

and x=4

enter it into a graphing calculator in one of the y= spots

in the other enter in y=0

then intersect the two points

orr you could do the quadratic equation..

b plus or minus the square root of (b squared minus 4(a)(c)) all divided by 2a.

so 2= a, b= -3 and c=-20

-3 plus or minus the square root of (-3squared minus 4*2*-20) all divided by 2*2

I know its mean, but I would help you if you actually showed you had tried the question and had some sort of idea of an answer :o)

you can use the quadratic formula

or

factorise it