Rational Numbers NCERT Exercise 9.2
Question 1: Find the sum:
(a) `5/4+(-11)/(4)`
Answer: `5/4+(-11)/(4)=4/5-(11)/4`
`=(5-11)/4=-6/4=-3/2`
(b) `5/3+3/5`
Answer: `5/3+3/5`
`=(25+9)/(15)=(34)/(15)`
(c) `(-9)/(10)+(22)/(15)`
Answer: `(-9)/(10)+(22)/(15)`
`=(-27+44)/(30)=(17)/(30)`
(d) `(-3)/(-11)+5/9`
Answer: `(-3)/(-11)+5/9`
`=(3)/(11)+5/9`
`=(27+55)/(99)=(82)/(99)`
(e) `(-8)/(19)+(-2)/(57)`
Answer: `(-8)/(19)+(-2)/(57)`
`=(-8)/(19)-(2)/(57)`
`=(-24-2)/(57)=(-26)/(57)`
(f) `-2/3+0`
Answer: When zero is added to any number, the value of number does not change.
`-2/3+0=-2/3`
(g) `-2\1/3+4\3/5`
Answer: `-2\1/3+4\3/5=-7/3+(23)/(5)`
`=(-35+69)/(15)=(34)/(15)`
Question 2: Find the value of following:
(a) `(7)/(24)-(17)/(36)`
Answer: `(7)/(24)-(17)/(36)`
`=(21-34)/(72)=-(13)/(72)`
(b) `(5)/(63)-621`
Answer: `(5)/(63)-621`
`=(5-39123)/(63)=-(39118)/(63)`
(c) `(-6)/(13)-715`
Answer: `(-6)/(13)-715`
`=(-6-9295)/(13)=(-9301)/(13)`
(d) `(-3)/(8)-(7)/(11)`
Answer: `(-3)/(8)-(7)/(11)`
`=(-33-56)/(88)=-(89)/(88)`
(e) `-2\1/9-6`
Answer: `-2\1/9-6=-(19)/(9)-6`
`=(-19-54)/(9)=-(73)/(9)`
Question 3: Find the product of following:
(a) `9/2xx(-7)/(4)`
Answer: `9/2xx(-7)/(4)=-(63)/(8)`
(b) `(3)/(10)xx-9`
Answer: `(3)/(10)xx-9=-(27)/(10)`
(c) `-6/5xx(9)/(11)`
Answer: `-6/5xx(9)/(11)=-(54)/(55)`
(d) `3/7xx(-2)/(5)`
Answer: `3/7xx(-2)/(5)=-(6)/(35)`
(e) `(3)/(11)xx2/5`
Answer: `(3)/(11)xx2/5=(6)/(55)`
(f) `(3)/(-5)xx(-5)/(3)`
Answer: `(3)/(-5)xx(-5)/(3)=1`
Question 4: Find the value of following:
(a) `-4÷2/3`
Answer: `-4÷2/3`
`=4xx3/2=-6`
(b) `-3/5÷2`
Answer: `-3/5÷2`
`=-3/5xx1/2=(-3)/(10)`
(c) `-4/5÷(-3)`
Answer: `-4/5÷(-3)`
`=-4/5xx(-1)/(3)=(4)/(15)`
(d) `-1/8÷3/4`
Answer: `-1/8÷3/4`
`=-1/8xx4/3=-1/6`
(e) `-(2)/(13)÷1/7`
Answer: `-(2)/(13)÷1/7`
`=-(2)/(13)xx7/1=-(14)/(13)`
(f) `-(7)/(12)÷(-2)/(13)`
Answer: `-(7)/(12)÷(-2)/(13)`
`=-(7)/(12)xx(-13)/(2)=(91)/(24)`
(g) `(3)/(13)÷(-4)/(65)`
Answer: `(3)/(13)÷(-4)/(65)`
`=(3)/(13)xx(-65)/(4)=-(15)/(4)`