Use the direct method to evaluate : (xy+4) (xy−4) - Vidyadip

Question

Use the direct method to evaluate : $(xy+4) (xy−4)$

✓

Answer

$(a+b) (a−b) $
$= a^2 − b^2(xy+4) (xy−4)$
$ = (xy)^2 − (4)^2$
$= x^2y^2 − 16$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "[4 marks sum]" from Identities→Identities — all question types→MATHS STD 8 question papers→ICSE Board STD 8 question papers→ICSE Board question paper generator→

Similar questions

Evaluate: $\frac{3}{8}+\frac{-5}{12}+\frac{3}{7}+\frac{3}{12}+\frac{-5}{8}+\frac{-2}{7}$

Construct a quadrilateral $ABCD$; if : $AB = 5 \ cm, BC = 6.5 \ cm, CD =4.8 \ cm, \angle B = 75^\circ$ and $\angle C = 120^\circ .$

If A$ = \{x \in W : 5 < x < 10\}, B = \{3, 4, 5, 6, 7\}$ and $C = \{x = 2n; n \in N$ and $n \leq 4\}$. Find : $B ∪ (A ∩ C)$

Find a single discount $($as a percent$)$ equivalent to following successive discounts: $20\%$ and $12\%$

At what rate percent of simple interest will the interest on $Rs.3750$ be one$-$fifth of itself in $4$ years? To what will it amount in $15$ years?

Find the amount and the compound interest on $₹ 10,000$ in $3$ years, if the rates of interest for the successive years are $10\%, 15\%,$ and $20\%$ respectively.

Divide : $\left(x^2+8 x+15\right)$ by $(x+5)$

If $3 x+\frac{1}{3 x}=3$, find: $9 x^2+\frac{1}{9 x^2}$

The curved surface area and the volume of a toy, cylindrical in shape, are $132\ cm^2$ and $462\ cm^3$ respectively. Find, its diameter and its length.

The sum of two numbers is $405$ and their ratio is $8 : 7$. Find the numbers.