Question

find the length and breadth of rectangle if area = 9l^2-3l-20​

Answer 1

Step-by-step explanation:

Here, l=(5.7±0.1)cm,b=(3.4±0.2)cm

Area, A = l×b=5.7×3.4=19.38cm

2

=19.0cm

2

(rounding off to two significant figures)

∴

A

△A

=±(

l

△l

+

b

△b

)

= ±(

5.7

0.1

+

3.4

0.2

)=±(

5.7×3.4

0.34+1.14

)=±

19.38

1.48

⇒△A=±

19.38

1.48

×A=±

19.38

1.48

×19.38=±1.48

△A=±1.5 (rounding off to two significant figures);

Area = (19.0±1.5)cm

2

.