chapter 11

ધોરણ 7 | విષય: Maths

સ્વાધ્યાય 11.1

સાચો જવાબ:


  • (i) $2^6$


    $$2 \times 2 \times 2 \times 2 \times 2 \times 2 = \mathbf{64}$$


  • (ii) $9^3$


    $$9 \times 9 \times 9 = 81 \times 9 = \mathbf{729}$$


  • (iii) $11^2$


    $$11 \times 11 = \mathbf{121}$$


  • (iv) $5^4$


    $$5 \times 5 \times 5 \times 5 = 25 \times 25 = \mathbf{625}$$


સાચો જવાબ:


  • (i) $6 \times 6 \times 6 \times 6$ $\implies$ $\mathbf{6^4}$




  • (ii) $t \times t$ $\implies$ $\mathbf{t^2}$




  • (iii) $b \times b \times b \times b$ $\implies$ $\mathbf{b^4}$




  • (iv) $5 \times 5 \times 7 \times 7 \times 7$ $\implies$ $\mathbf{5^2 \times 7^3}$




  • (v) $2 \times 2 \times a \times a$ $\implies$ $\mathbf{2^2 \times a^2}$




  • (vi) $a \times a \times a \times c \times c \times c \times c \times d$ $\implies$ $\mathbf{a^3 \times c^4 \times d}$




સાચો જવાબ:


  • (i) $512$


    $$2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 = \mathbf{2^9}$$


  • (ii) $343$


    $$7 \times 7 \times 7 = \mathbf{7^3}$$


  • (iii) $729$


    $$3 \times 3 \times 3 \times 3 \times 3 \times 3 = \mathbf{3^6}$$

    (અથવા $9^3$)




  • (iv) $3125$


    $$5 \times 5 \times 5 \times 5 \times 5 = \mathbf{5^5}$$


સાચો જવાબ:


  • (i) $4^3$ અને $3^4$





    • $4^3 = 4 \times 4 \times 4 = 64$




    • $3^4 = 3 \times 3 \times 3 \times 3 = 81$




    • અહીં, $81 > 64$ હોવાથી મોટી સંખ્યા ન્હ $3^4$ છે.






  • (ii) $5^3$ અને $3^5$





    • $5^3 = 5 \times 5 \times 5 = 125$




    • $3^5 = 3 \times 3 \times 3 \times 3 \times 3 = 243$




    • મોટી સંખ્યા ન્હ $3^5$ છે.






  • (iii) $2^8$ અને $8^2$





    • $2^8 = 256$




    • $8^2 = 64$




    • મોટી સંખ્યા ન્હ $2^8$ છે.






  • (iv) $100^2$ અને $2^{100}$





    • $100^2 = (10^2)^2 = 10^4 = 10,000$




    • $2^{100}$ એ ખૂબ જ મોટી સંખ્યા છે ($10^4$ કરતાં અનેકગણી મોટી).




    • મોટી સંખ્યા ન્હ $2^{100}$ છે.






  • (v) $2^{10}$ અને $10^2$





    • $2^{10} = 1024$




    • $10^2 = 100$




    • મોટી સંખ્યા ન્હ $2^{10}$ છે.






સાચો જવાબ:


  • (i) $648$


    $$648 = 2 \times 2 \times 2 \times 3 \times 3 \times 3 \times 3 = \mathbf{2^3 \times 3^4}$$


  • (ii) $405$


    $$405 = 3 \times 3 \times 3 \times 3 \times 5 = \mathbf{3^4 \times 5}$$


  • (iii) $540$


    $$540 = 2 \times 2 \times 3 \times 3 \times 3 \times 5 = \mathbf{2^2 \times 3^3 \times 5}$$


  • (iv) $3,600$


    $$3600 = 2 \times 2 \times 2 \times 2 \times 3 \times 3 \times 5 \times 5 = \mathbf{2^4 \times 3^2 \times 5^2}$$


સાચો જવાબ:


  • (i) 2×103


    2×1000=2000


  • (ii) 72×22


    49×4=196


  • (iii) 23×5


    8×5=40


  • (iv) 3×44


    3×256=768


  • (v) 0×102


    0×100=0


  • (vi) 52×33


    25×27=675


  • (vii) 24×32


    16×9=144


  • (viii) 32×104


    9×10000=90000


સાચો જવાબ:


  • (i) $(-4)^3$


    $$(-4) \times (-4) \times (-4) = \mathbf{-64}$$


  • (ii) $(-3) \times (-2)^3$


    $$(-3) \times [(-2) \times (-2) \times (-2)] = (-3) \times (-8) = \mathbf{24}$$


  • (iii) $(-3)^2 \times (-5)^2$


    $$[(-3) \times (-3)] \times [(-5) \times (-5)] = 9 \times 25 = \mathbf{225}$$


  • (iv) $(-2)^3 \times (-10)^3$


    $$[(-2) \times (-2) \times (-2)] \times [(-10) \times (-10) \times (-10)] = (-8) \times (-1000) = \mathbf{8000}$$


સાચો જવાબ:


  • (i) $2.7 \times 10^{12}$; $1.5 \times 10^8$





    • બંને સંખ્યાઓમાં $10$ ની ઘાત જોઈએ તો $10^{12}$ એ $10^8$ કરતાં મોટી છે.




    • તેથી, $2.7 \times 10^{12} > 1.5 \times 10^8$






  • (ii) $4 \times 10^{14}$; $3 \times 10^{17}$





    • અહીં $10^{17}$ વાળી સંખ્યા મોટી છે ($10^{17} > 10^{14}$).




    • તેથી, $3 \times 10^{17} > 4 \times 10^{14}$






સ્વાધ્યાય 11.2

સાચો જવાબ:


  • (i) $3^2 \times 3^4 \times 3^8$


    $$3^{2 + 4 + 8} = \mathbf{3^{14}}$$


  • (ii) $6^{15} \div 6^{10}$


    $$6^{15 - 10} = \mathbf{6^5}$$


  • (iii) $a^3 \times a^2$


    $$a^{3 + 2} = \mathbf{a^5}$$


  • (iv) $7^x \times 7^2$


    $$\mathbf{7^{x + 2}}$$


  • (v) $(5^2)^3 \div 5^3$


    $$5^{2 \times 3} \div 5^3 = 5^6 \div 5^3 = 5^{6 - 3} = \mathbf{5^3}$$


  • (vi) $2^5 \times 5^5$


    $$(2 \times 5)^5 = \mathbf{10^5}$$


  • (vii) $a^4 \times b^4$


    $$\mathbf{(ab)^4}$$


  • (viii) $(3^4)^3$


    $$3^{4 \times 3} = \mathbf{3^{12}}$$


  • (ix) $(2^{20} \div 2^{15}) \times 2^3$


    $$2^{20 - 15} \times 2^3 = 2^5 \times 2^3 = 2^{5 + 3} = \mathbf{2^8}$$


  • (x) $8^t \div 8^2$


    $$\mathbf{8^{t - 2}}$$


સાચો જવાબ:


  • (i) 3×3223×34×4​


    31×2523×34×22​=25×3123+2×34​=25−5×34−1=20×33=33


  • (ii) [(52)3×54]÷57


    [56×54]÷57=510÷57=510−7=53


  • (iii) 254÷53


    (52)4÷53=58÷53=58−3=55


  • (iv) 21×1133×72×118​


    (3×7)×1133×72×118​=31−1×72−1×118−3=30×71×115=7×115


  • (v) 34×3337​


    34+337​=3737​=37−7=30=1


  • (vi) 20+30+40


    1+1+1=3


  • (vii) 20×30×40


    1×1×1=1


  • (viii) (30+20)×50


    (1+1)×1=2×1=2


  • (ix) 43×a328×a5​


    (22)3×a328×a5​=26×a328×a5​=28−6×a5−3=22×a2=(2a)2(અથવા 4a2)


  • (x) (a3a5​)×a8


    a5−3×a8=a2×a8=a2+8=a10


  • (xi) 45×a5b245×a8b3​


    45−5×a8−5×b3−2=40×a3×b1=a3b


  • (xii) (23×2)2


    (23+1)2=(24)2=24×2=28


સાચો જવાબ:


  • (i) 10×1011=10011





    • ડા.બા.: 101×1011=1012




    • જ.બા.: 10011=(102)11=1022




    • 1012=1022⟹ ખોટું






  • (ii) 23>52





    • 23=8 અને 52=25




    • 8>25 શક્ય નથી ⟹ ખોટું






  • (iii) 23×32=65





    • ડા.બા.: 8×9=72




    • જ.બા.: 65=7776




    • 72=7776⟹ ખોટું






  • (iv) 30=(1000)0





    • 30=1 અને (1000)0=1




    • 1=1⟹ ખરું






સાચો જવાબ:


  • (i) 108×192





    • 108=22×33




    • 192=26×31




    • 108×192=(22×33)×(26×31)=22+6×33+1=28×34






  • (ii) 270





    • 270=2×3×3×3×5=2×33×5






  • (iii) 729×64





    • 729=36




    • 64=26




    • 729×64=26×36






  • (iv) 768





    • 768=2×2×2×2×2×2×2×2×3=28×3






સાચો જવાબ:


  • (i) $108 \times 192$





    • $108 = 2^2 \times 3^3$




    • $192 = 2^6 \times 3^1$




    • $108 \times 192 = (2^2 \times 3^3) \times (2^6 \times 3^1) = 2^{2+6} \times 3^{3+1} = \mathbf{2^8 \times 3^4}$






  • (ii) $270$





    • $270 = 2 \times 3 \times 3 \times 3 \times 5 = \mathbf{2 \times 3^3 \times 5}$






  • (iii) $729 \times 64$





    • $729 = 3^6$




    • $64 = 2^6$




    • $729 \times 64 = \mathbf{2^6 \times 3^6}$






  • (iv) $768$





    • $768 = 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 3 = \mathbf{2^8 \times 3}$






સ્વાધ્યાય 11.3

સાચો જવાબ:


  • (a) $279404$


    $$279404 = \mathbf{2 \times 10^5 + 7 \times 10^4 + 9 \times 10^3 + 4 \times 10^2 + 0 \times 10^1 + 4 \times 10^0}$$


  • (b) $3006194$


    $$3006194 = \mathbf{3 \times 10^6 + 0 \times 10^5 + 0 \times 10^4 + 6 \times 10^3 + 1 \times 10^2 + 9 \times 10^1 + 4 \times 10^0}$$


  • (c) $2806196$


    $$2806196 = \mathbf{2 \times 10^6 + 8 \times 10^5 + 0 \times 10^4 + 6 \times 10^3 + 1 \times 10^2 + 9 \times 10^1 + 6 \times 10^0}$$


  • (d) $120719$


    $$120719 = \mathbf{1 \times 10^5 + 2 \times 10^4 + 0 \times 10^3 + 7 \times 10^2 + 1 \times 10^1 + 9 \times 10^0}$$


  • (e) $20068$


    $$20068 = \mathbf{2 \times 10^4 + 0 \times 10^3 + 0 \times 10^2 + 6 \times 10^1 + 8 \times 10^0}$$


સાચો જવાબ:


  • (a) $8 \times 10^4 + 6 \times 10^3 + 0 \times 10^2 + 4 \times 10^1 + 5 \times 10^0$


    $$80000 + 6000 + 0 + 40 + 5 = \mathbf{86405}$$


  • (b) $4 \times 10^5 + 5 \times 10^3 + 3 \times 10^2 + 2 \times 10^0$


    $$400000 + 0 + 5000 + 300 + 0 + 2 = \mathbf{405302}$$


  • (c) $3 \times 10^4 + 7 \times 10^2 + 5 \times 10^0$


    $$30000 + 0 + 700 + 0 + 5 = \mathbf{30705}$$


  • (d) $9 \times 10^5 + 2 \times 10^2 + 3 \times 10^1$


    $$900000 + 0 + 0 + 200 + 30 + 0 = \mathbf{900230}$$


સાચો જવાબ:


  • (i) $5,00,00,000$


    $$\mathbf{5 \times 10^7}$$


  • (ii) $70,00,000$


    $$\mathbf{7 \times 10^6}$$


  • (iii) $3,18,65,00,000$


    $$\mathbf{3.1865 \times 10^9}$$


  • (iv) $3,90,878$


    $$\mathbf{3.90878 \times 10^5}$$


  • (v) $39087.8$


    $$\mathbf{3.90878 \times 10^4}$$


  • (vi) $3908.78$


    $$\mathbf{3.90878 \times 10^3}$$


સાચો જવાબ:


  • (i) $5,00,00,000$


    $$\mathbf{5 \times 10^7}$$


  • (ii) $70,00,000$


    $$\mathbf{7 \times 10^6}$$


  • (iii) $3,18,65,00,000$


    $$\mathbf{3.1865 \times 10^9}$$


  • (iv) $3,90,878$


    $$\mathbf{3.90878 \times 10^5}$$


  • (v) $39087.8$


    $$\mathbf{3.90878 \times 10^4}$$


  • (vi) $3908.78$


    $$\mathbf{3.90878 \times 10^3}$$


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