Question

x^2-4x-21
Solve by qudratic formula

Answer 1

Answer:

x = -3 , x = 7

Step by step explanation:

Step 1 : First we have to do middle term splitting

x^2 -7x +3x -21

Step 2 : Now we have to take terms that r common between them

x(x-7) + 3(x-7)

Step 3 : Now make 2 brackets

(x+3) , (x-7)

Step 4 : Now we have to find the value of x by equating

x+3=0

x= -3

x-7=0

x= 7

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Answer 2

Answer:

we should use quadratic formula so ,formula is _b+_under root b^2_4ac by 2a

Explanation:

a=1 b=-4 c=-21

apply in formula

-(-4)+_ _/(-4)^2_4(1)(_21)

‐---------------------------

2(1)

4+- _/16+84

= ----------------------

2

4+-_/100

= ---------------

2

4+- 10

-----------

= 2

= 4+10 4-10

------- ; ---------

2 2

= 14by 2 ; -6by 2

= 7,-3 are zeros of the polynomial