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Polynomials — Maths STD 9 — Question

Gujarat BoardEnglish MediumSTD 9MathsPolynomials2 Marks
Question
Evaluate $105 \times 106$ without multiplying directly.
✓

Answer

Firstly, write 105 as $100+5$ and 106 as $100+6$.
$\therefore 105 \times 106=(100+5) \times(100+6)$
$=(100)^2+(5+6) 100+(5 \times 6)$
${\left[\because(x+a)(x+b)=x^2+(a+b) x+a b\right]}$
$=10000+11 \times 100+30$
$=10000+1100+30=11130$

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