Question

(5x-8)(4x+1) expand and simplify

Answer 1

5x*4x=20x^2
-8*4x=32x
5x*1=5x
-8*1=-8
20x^2+32x+5x-8
20x^2+37x-8

Answer 2

wouldn't (-8*4x)= -32x

Answer 3

Yes it would, my bad

Answer 4

So then the -32x+5x would be -27x

Answer 5

so 20x^2-27x+8, is your final value, just walk back through the steps to identify where easy came from.

Answer 6

ohhh thank you

Answer 7

each*

Answer 8

is x^2 mean squared

Answer 9

yes, it means x to the power of 2
so x^2 is squared x^3 is cubed and so on

Answer 10

oh alright thank you :)

Answer 11

thanx

Answer 12

props also to paandaabear

Answer 13

why is it 20^2 and not just 20 ?

Answer 14

because quadratics are in ax^2+bx+c form
x*x=x^2

Answer 15

you can multiply out 5*4 to get 20 but there is an x term, which cant multiply but we use the notation as though it could, and since a number multiplied by itself is the same as squaring it, the same applies to x
if we were to replace x with a value say x=3, then for x^2 we get 3^2 = 9

Answer 16

ohh yeah okay thanks

Answer 17

would (x-2)^2 be x^2-4x-4

Answer 18

correct

Answer 19

okay and would (5x+4)(5x-4) be 10x-40x-16 ??

Answer 20

no, its not 2*5x its 5x*5x , so
= (5x*5x)-(5x*4)+(4*5x)-(4*4)
= 25x^2-20x+20x-16
= 25x^2-16, since -20x+20x = 0

Answer 21

5x*5x = 5^2 and x^2 = 25x^2, which is really 25 (x^2)
5*5x = 5^2 and x^1 = 25x

Answer 22

ohh so whats the actual answer?

Answer 23

for which?
(5x+4)(5x-4)?

Answer 24

yeah

Answer 25

= (5x*5x)-(5x*4)+(4*5x)-(4*4)
= 25x^2-20x+20x-16
= 25x^2-16

Answer 26

oh thank you soo much

Answer 27

glad to help