Question
Evaluate $\left(-8 x^2 y^5\right) \times(-20 x y)$ for $x=2.5$ and $y=1$
✓
Answer
To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e. $a ^{ m } \times a ^{ n }$ $=a^{m+n}$.
We have:
$\left(-8 x^2 y^6\right) \times(-20 x y)$
$=[(-8) \times(-20)] \times\left(x^2 \times x\right) \times\left(y^6 \times y\right)$
$=[(-8) \times(-20)] \times\left(x^2+1\right) \times\left(y^6+1\right)$
$=160 x^3 y^7$
$\left(-8 x^2 y^6\right) \times(-20 x y)=160 x^3 y^7$
Substituting $x=2.5$ and $y=1$ in the result, we get:
$=160 x^3 y^7$
$=160(2.5)^3(1)^7$
$=160 \times 15.625$
$=2500$
Thus, the answer is 2500 .
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Construct a parallelogram PQRS in which QR = 6cm, PQ = 4cm and $\angle\text{PQR}=60^\circ.$
→Find (x + y) ÷ (x − y), if
$\text{x}=\frac{1}{4},\text{y}=\frac{3}{2}$
→$\text{x}=\frac{1}{4},\text{y}=\frac{3}{2}$
Factorize :
44x² – x – 3
The dimensions of a cuboid are in the ratio $5: 3: 1$ and its total surface area is $414 m^2$. Find the dimensions.
→What is the length of the side of a cube whose volume is $275 cm^3$. Make use of the table for the cube root.
→How many bricks each of size $25 cm \times 10 cm \times 8 cm$ will be required to build a wall 5 m long, 3 m high and 16 cm thick assuming that the volume of sand and cement used in the construction is negligible?
→The histogram given below shows the number of literate females in the age group of 10 to 40 years. Study the histogram carefully and answer the question that follow:
→
- Write the classes, assuming that all the classes are of equal width.
- What is the class width?
- In which age group are the literate females the least?
- In which age group is the number of literate females the highest?
The radius and height of a cylinder are in the ratio $7: 2$. If the volume of the cylinder is $8316 cm^3$, find the total surface area of the cylinder.
→Simple interest on a sum of money for 2 years at $6\frac{1}{2}\%$ per annum is Rs. 5200. What will be the compound interest on the sum at the same rate for the same period?
→A classroom is 7 m long, 6 m broad and 3.5 m high. Doors and windows occupy an area of $17 m^2$. What is the cost of white-washing the walls at the rate of Rs. 1.50 per $m ^2$.
→