Question

Solve using the quadratic formula. Leave Irrational answers in radical form.

x2 + x - 20 = 0

The solutions are

and

Answer 1

x1= 4 , x2= -5

Explanation:

put in calculator MOD 5 3

a= 1 b= 1 c= -20

Answer 2

x1 = 4

x2 = -5

Explanation:

There is a formula to solve the quadratic equations, which is:

[-b +- √ (b² - 4 ac) ] / (2a)

Quadractic equations have this look:

ax² + bx + c = 0

You need to stablish the numbers:

where a, is the number with x², b the x and c, the independent term.

x² + x - 20 = 0 For this case:

a = 1 ; b = 1 ; c = -20. We replace in the formula

[-1 +- √ (1² - 4 1 (-20)) ] / (2 .1)

(-1 + √81) / 2 = 4

(-1 - √81) / 2 = -5