Download App

Identities — MATHS STD 8 — Question

ICSE BoardEnglish MediumSTD 8MATHSIdentities4 Marks
Question
Evaluate: $\left(3 \mathrm{x}-\frac{1}{2 \mathrm{y}}\right)\left(3 \mathrm{x}+\frac{1}{2 \mathrm{y}}\right)$
✓

Answer

$ \left(3 x-\frac{1}{2 y}\right)\left(3 x+\frac{1}{2 y}\right)$
$ =3 x\left(3 x+\frac{1}{2 y}\right)-\frac{1}{2 y}\left(3 x+\frac{1}{2 y}\right)$
$ =9 x^2+\frac{3 x}{2 y}-\frac{3 x}{2 y}-\frac{1}{4 y^2}$
$ =9 x^2-\frac{1}{4 y^2}$

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

Find a single discount $($as a percent$)$ equivalent to following successive discounts: $20\%$ and $12\%$
→
Evaluate: $\frac{3}{8}+\frac{-5}{12}+\frac{3}{7}+\frac{3}{12}+\frac{-5}{8}+\frac{-2}{7}$
→
The present age of a man is twice that of his son. Eight years hence, their ages will be in the ratio $7 : 4$. Find their present ages
→
A parallelogram has sides of $20\  cm$ and $30 \ cm$. If the distance between its shorter sides is $15\  cm$; find the distance between the longer sides.
→
Compute: $(243)^{\frac{2}{5}} \div(32)^{-\frac{2}{5}}$
→
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 : $A ∩ (B ∪ C)$
→
A man sells $12$ articles for $Rs. 80$ gaining $33 \frac{1}{3} \%$. Find the number of articles bought by the man for $Rs. 90$.
→
Construct an angle $PQR = 80^\circ$ . Draw a line parallel to $PQ$ at a distance of $3 \ cm$ from it and another line parallel to $QR$ at a distance of $3.5 \ cm$ from it. Mark the point of intersection of these parallel lines as $A.$
→
If $3$ men or $6$ boys can finish a work in $20$ days, how long will $4$ men and $12$ boys take to finish the same work?
→
A can do a piece of work in $10$ days, $B$ in $12$ days, and $C$ in $15$ days. All begin together but $A$ leaves the work after $2$ days and $B$ leaves $3$ days before the work is finished. How long did the work last?
→