Question

calculate 1-2+3-4+5-6 ________ +19-20

Answer 1

Answer:

-10

Step-by-step explanation:

Take two terms one by one and bracket it.like

(1-2)+(3-4)+(5-6)+(7-8)+..........+(19-20)

= -1-1-1-1-...-1

Now think you made 10 brackets because here is 1-20 and you paired up with each two.that means you have 10 no of -1.so your answer IS 10*(-1)= -10

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