Question

Which numbers should be multiplied to obtain 165^2 - 123^2?

a.42 and 42

b.42 and 288

c.1,764 and 1,764

d.4,202 and 4,248

Answer 1

hint: Difference of squares rule

\[\Large a^2 - b^2 = (a-b)(a+b)\]

Answer 2

165 is not a perfect square

but 165^2 is

Answer 3

is it b?
@jim_thompson5910

Answer 4

@SolomonZelman

Answer 5

yes you are correct

Answer 6

can you help me with another one? @jim_thompson5910

Answer 7

sure I can do one more

Answer 8

which of the following is an actual zero of F(x)=x^3+5x^2-4x-20
a.-20
b.-5
c.1
d.4

Answer 9

@jim_thompson5910

Answer 10

I think the answer is b but im not sure.

Answer 11

a value is a zero (or root) if plugging it in gives 0

Answer 12

what is f(-20)?

Answer 13

ohhh so the answer would be A then

Answer 14

@jim_thompson5910

Answer 15

what is f(-20)?

Answer 16

f(x)=x^3+5x^2-4x-20

f(-20)=(-20)^3+5(-20)^2-4(-20)-20

f(-20)=???

Answer 17

I don't know

Answer 18

use a calculator to evaluate (-20)^3+5(-20)^2-4(-20)-20

Answer 19

i got -5940

Answer 20

if you don't have a calculator, you can type that expression directly into google or wolfram alpha and it will compute it

Answer 21

i typed it into wolfram alpha and that's what it gave me sooo idk

Answer 22

good, so because that result is NOT equal to 0, that means x = -20 is NOT a root for f(x)=x^3+5x^2-4x-20

Answer 23

a value is only a root if you get f(x) = 0

Answer 24

ok so A is wrong

Answer 25

yes because f(x) = -5940 when x = -20

Answer 26

okay what about c?

Answer 27

what is f(1) ?

Answer 28

wait I got it the answer is b -5 because (-5)^3+5(-5)^2-4(-5)-20=0 @jim_thompson5910

Answer 29

very good

Answer 30

thanks for your help :)

Answer 31

you're welcome