Identities

What is identity mean?

• It is equality which set for all x

• It is used to find variables

• it is true for x = 1

• I don't know

7x + 3 - 7x = 3 is it an identity?

• Yes

• No

Which of the following is NOT an identity?

• 3y + 5y = 8y

• 9y - 4y = 5y

• (5y)(10y) = 50y

• 20y $\div$ 4 = 5y

 $\left(x+y\right)\left(x-y\right)=x^2-y^2$ 

 Determine whether the above is/isn't an identity.

• Yes

• No

• Partially correct
  

 $x^2-\left(x-3y\right)\left(x+3y\right)=9y^2$  

Is it an identity?

• Yes

• No

• Partially correct

• it is correct only when x = 0

if
 $3\left(2x+4\right)\equiv Bx+C$ 
, find C

• 3

• 4

• 12

• 24

if
 $\left(x-2\right)\left(2x-5\right)\equiv2x^2+Ax+10$ 
 , find A.

• -9

• -9x

• 1

• x

if
 $\left(4x+B\right)\left(6x+5\right)\equiv Cx^2+2x-15$ 
 , find C.

• -3

• 4

• 6

• 24

if
 $\left(4x+B\right)\left(6x+5\right)\equiv Cx^2+2x-15$ 
 , find B.

• -3

• 4

• 6

• 24

if
 $x^2+a\equiv\left(x+3\right)\left(x+b\right)+11$ 
,find a.