jahajahaja jahajahaja
  • 01-09-2016
  • Mathematics
contestada

What are the zeros of f(x)=x^2+x-20?
A.x=-2 and x=10
B.x=-10 and x=2
C.x=-5 and x=4
D.x=-4 and x=5

Respuesta :

dalendrk
dalendrk dalendrk
  • 02-09-2016
f(x) = x² + x - 20 = x² + 5x - 4x - 20 = x(x + 5) - 4(x + 5) = (x + 5)(x - 4)

f(x) = 0 ⇔ (x + 5)(x - 4) = 0 ⇔ x + 5 = 0 or x - 4 = 0 ⇒ x = -5 or x = 4

Answer: C. x = -5 and x = 4.
Answer Link

Otras preguntas

how are plains formed
a rectangular prism has a length of 2x^2+2x-24 over 4x^2+x, a width of x^2+x-6 over x+4, and a height of 8x^2+2x over x^2-9. For all values of x for which it is
what are some physical changes that occur at school? at home ? in nature ?
What does a journal written by frontier settlers most likely tell you about Manifest Destiny?
how can you tell the difference between additive comparison and multiplication comparison
Give a counter example to this statement. The quotient of two fractions between 0 and 1 is always a whole number.
what is 8-4/5f>-14-2f
plz help me solve this question how many remain when 87 is divided by 9
Prove the identity: cos(3x) + cos(x) = 2cos(2x)cos(x) I'm almost done with my homework, just got stuck on this one.
Write 75 as the product of its prime factors. (2 marks)