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Algebraic Expressions and Identities — MATHS STD 8 — Question

Gujarat BoardEnglish MediumSTD 8MATHSAlgebraic Expressions and Identities2 Marks
Question
Simplify $a (a^2+ a + 1) + 5$ and find its value for $a = - 1$
✓

Answer

We have $a(a^2+ a + 1) + 5$
$a(a^2+ a + 1) + 5$
$= a^3+ a^2+ a + 5$
Substituting $a = -1$ in the expression
$a^3+ a^2+ a + 5$
$= (-1)^3+ (-1)^2- 1 + 5$ [$\because$$(-1)^n= 1$ if $n$ =even, $(-1)^n= -1$ if $n$ = odd]
$= - 1 + 1 - 1 + 5$
$= 4$

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