x2-x-20= what is the answer
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Answer:
22x is rhe answer
Step-by-step explanation:
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Answered by
1
Find two numbers whose product is 20
and whose difference is 1
. The pair 5 , 4 works.
Hence
x2−x−20
=(x−5)(x+4) .
So solutions are
x=5 or x=−4
.Explanation:
(x−a)(x+b)
=x2−(a−b)x−ab
Matching this against
x2−x−20
we see that if we can find a and b
such that a−b=1 and ab=20
, then we can factor the quadratic into two linear terms.
The pair a=5 , b=4 works, giving usx2−x−20
=(x−5)(x+4)
This will be 0
when (x−5)=0 or (x+4)=0 , which is when
x=5 or x=−4.
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