Question

use suitable identity to expand
(x-4) (x+5) ​

Answer 1

Answer:

x=4

Step-by-step explanation:

look this identity is pretty simple:

SO,

= (x-4) (x+5)

= x(x +5) - 4(x+5)

=  $x^{2} +5x -4x-20$

= $x^{2}$ +x-20

hence the answer we will get after solving the quadratic equation will be (x-4) (x+5)

ALSO

x-4 = 0                       OR               x+5=0

x=4                                                  x=-5

BUT,

x cant equal to -5

HENCE THE ANSWER IS x=4

x=4                    

Answer 2

Step-by-step explanation:

We need to expand (x−

3

2

y)

3

Suitable identities is (x−y)

3

=x

3

−3x

2

y+3xy

2

−y

3

The value of (x−

3

2

y)

3

is

= (x)

3

−3(x)

2

(

3

2

y)+3(x)(

3

2

y)

2

−(

3

2

y)

3

= x

3

−2x

2

y+

3

4

xy

2

−

27

8

y

3

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