Question

(а - 1)(а^2+а +1) - а^2 (а - 8) при а = дробь 2/9

Answer 1

(а - 1)(а^2+а +1) - а^2 (а - 8)=а^3 - 1-а^3+8а^2=8а^2 - 1, а=2/9, 8×(2/9)^2 - 1=8×4/81 - 1=32/81 - 1=32/81-81/81=(32-81)/81=-49/81

Answer 2

To evaluate this expression for a = 2/9, we can simply substitute 2/9 for every instance of "a" in the expression and simplify the result.

Starting with the first term: (a - 1)(a^2 + a + 1) = (2/9 - 1)((2/9)^2 + 2/9 + 1) = (-7/9)(4/81 + 2/9 + 1) = (-7/9)(13/27) = -91/243

Now for the second term: a^2(a - 8) = (2/9)^2(2/9 - 8) = (4/81)(-70/9) = -280/243

Putting it all together, we get: (а - 1)(а^2+а +1) - а^2 (а - 8) = (-91/243) - (280/243) = -371/243

Therefore, the value of the expression when a = 2/9 is -371/243.