Answer✒️

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-20

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Explaination✒️

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#1 = Subtitute ( a = 2 )

( b = -1)

-7a²b + 2a³-b²

#2 put a (a = 1) and (b = -1)

#3 Now Calculate or Solve

• -7( -1)²(2)+ 2 (-1)³-(2)²= -20
• -14 -2 -4 = -20
• -20

Final Answer : -20