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Exercise 8.2

Find the Sum.

(i) 54 + −114

= 5−114 =

(ii) 53 + 35

LCM of 3 and 5 is

2515 + 915 =

(iii) −910 + 2215

LCM of 10 and 15 is

−2730 + 4430 =

(iv) −3−11 + 59

LCM of 11 and 9 is

2799 + 5599 =

(v) −819 + −257

LCM of 19 and 57 is

−2457 + −257 =

(vi) −23 + 0

LCM of 3 and 1 is

−23 + 03 =

(vii) -213 + 435

LCM of 3 and 5 is

−3515 + 6915 =

Find.

(i)724 - 1736

Instruction

The least common denominator (LCD) of 24 and 36 is .

Convert 724 to 2172 (since 7×3=21 and 24×3=72).

Convert 1736 to 3472 (since 17×2=34 and 36×2=72).

Substract 2172 - 3472 = /.

(ii) 563 - −621

Firstly we will take the LCM of 63 and 21.

563 - −621 = 5×163×1 - −6×321×3 = (/63) - (/63)

5−−1863 = 5+1863 = /

(iii) −613 - −715

Firstly we will take the LCM of 13 and 15.

−613 - −715 = −6×1513×15 - 7×1315×13 = (/195) - (/195)

−90−−91195 = −90+91195 = /

(iv) −38 - 711

Firstly we will take the LCM of 8 and 11.

−38 - 711 = −3×118×11 - 7×811×8 = /88 - /88

−33−5688 = −8988 = -1(/)

(v) -219 - 6

-219 - 6

−199 - 61 = −19×19×1 - 6×91×9 = /9 - /9

−19−549 = −739 = -8(/)

Find the product.

(i)92 × −74

92 × −74 = 9×−72×4

= /8 = -7(/)

(ii)310 × −9

310 × −9 = /10 = -2(/)

(iii)−65 × 911

−65 × 911 = −6×95×11

= /

(iv)37 × −25

37 × −25 = 3×−27×5

= /

(v)311 × 25

311 × 25 = 3×211×5

= /

(vi)3−5 × −53

3−5 × −53 = 3×−5−5×3

= / =

Find the value of the numbers.

(i)(-4)÷23

(-4)÷23 = (-4) × 32 =

(ii)−35 ÷ 2

−35 ÷ 2 = −35 × 12 = −3×15×2

= /

(iii)−45 ÷ (-3)

−45 ÷ (-3) = −45 × 1−3 = −4×15×−3

= /

(iv)−18 ÷ 34

−18 ÷ 34 = −18 × 43 = −1×12×3

= /

(v)−213 ÷ 17

−213 ÷ 17 = −213 × 71 = −2×713×1

= -1(/)

(vi)−712 ÷ −213

−712 ÷ −213 = −712 × 13−2 = −7×1312×−2

= 3(/)

(vii)313 ÷ −465

313 ÷ −465 = 313 × 65−4 = 3×6513×−4

= -3(/)