Question

Solve. 5x2 – 20 = 0

x = 5 and x = 4

x = 4 and x = 2

x = –5 and x = 20

x = 2 and x = –2

Answer 1

@RadEn

Answer 2

You can start by:
Dividing both the sides by 5..

Answer 3

5x^2-4=0

Answer 4

x^2 - 4 = 0

Answer 5

factorize by using the difference squares formula
a^2 - b^2 = (a+b)(a-b)

Answer 6

And you can use here :
\[x^2 - a^2 = (x + a) (x - a)\]

Answer 7

Or if you don't wanna do this, then add 4 both the sides and then take square root both the sides.

Answer 8

so,... whats the answer ?

Answer 9

@RadEn

Answer 10

its not B

Answer 11

@waterineyes

Answer 12

Who told you that answer is B?

Answer 13

\(x^2 - 4 = 0\)

Add 4 both the sides and tell me what did you get?

Answer 14

well, look at how the factorization works
x^2 - 4 = 0
x^2 - 2^2 = 0
use the diff square formula,
(x+2)(x-2) = 0
solve for x
find the zeroes by make each factor be zero
first, x+2=0
subtract by 2 from both sides,
x+2-2 = 0-2
x = -2

do for the rest!

Answer 15

I dont really have to do the rest because there isnt another -2 in the other choices.

Answer 16

hehe, good tricky :)

Answer 17

do for the rest is actually for your own knowledge and not for answer choices you are given with..

Answer 18

ok, show to us how to solve of
x - 2 = 0 ?