7th Grade > Mathematics
EXPONENTS AND POWERS MCQs
:
Steps: 1 Mark
Answer: 1 Mark
45=(4)×(4)×(4)×(4)×(4)
⇒45=1024
54=(5)×(5)×(5)×(5)
⇒54=625
The difference between 45 and 54 is
45−54=1024−625
⇒45−54=399
The difference between 45 and 54 is 399.
:
Concept: 1 Mark
Answer: 1 Mark
Consider, 30=(1000)0
L.H.S. is 30=1 [ ∵a0 = 1]
and R.H.S. (1000)0=1 [ ∵a0 = 1]
⇒ L.H.S. = R.H.S.
⇒30=(1000)0.
∴ It is true.
We should remember that any non-zero number raised to the power 0 is always equal to 1.
:
Application: 1 Mark
Steps: 1 Mark
Answer: 1 Mark
Consider,
84×143×5×3445×73×62
84=(23)4=212
143=(2×7)3=23×73
45=(22)5=210
62=(2×3)2=22×32
On substituting the values we get:
212×23×73×5×34210×73×22×32
=212+3−10−2×73−3×5×34−2 [∵ aman=am−n]
=23×5×32 [∵a0=1]
=8×5×9
=360
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Concept: 1 Mark
Application: 1 Mark
Answer: 1 Mark
Let the number be x.
Given that,
(x)×(25)=78125
x=3125
⇒ The required number is 3125
Now,
3125=5×5×5×5×5
⇒3125=55
Now, if the number was multiplied by (−5)×(5) then the product=(−5)×(5)×3125 = −78125
:
Conversion: 1 Mark
Difference: 1 Mark
Standard form: 1 Mark
As per the question
The amount shopkeeper A has = Rs 34265.
The amount shop keeper B has = 432500 paise ⇒ Rs 4325.
Difference = Rs 34265 - Rs 4325 = Rs 29940.
The standard form of Rs 29940.
29940=2.994×104
The difference in rupees is 2.994×104
:
Formula: 1 Mark
Application: 1 Mark
Answer: 2 Marks
Given that
The ball is released from a height of x m
Height reached after first bounce =x2
Height reached after second bounce =x4=x22
Height reached after third bounce =x8=x23
Height reached after fourth bounce =x16=x24
Height reached after fifth bounce =x32=x25
Height reached after sixth bounce =x64=x26
Height reached after seventh bounce =x128=x27
Height reached after eight bounce =x256=x28
∴ Product of first 9 heights =x×x2×x22×x23×x24×x25×x26×x27×x28
=x(1+1+1+1+1+1+1+1+1)2(1+2+3+4+5+6+7+8)
(∵ab×ac = ab+c)
=x9236
The product of heights after 8 bounces =x9236
:
Each option: 1 Mark
i)512=2×2×2×2×2×2×2×2×2=29
ii)343=7×7×7=73
iii)729=3×3×3×3×3×3=36
:
Step: 2 Marks
Application: 1 Mark
Answer: 1 Mark
The area of land owned by X is
=34 m2=81 m2
The value of given property is
=(81)×(50)=Rs.4050
The area of land owned by Y is
43 m2=64 m2
The value of given property is
=(64)×(50)=Rs.3200
⇒ Value of property owned by X is greater than property owned by Y.
:
Each: [2 Marks]
i)(58)−7×(85)−5
=5−78−7×8−55−5
=5−75−5×8−58−7
=5(−7)−(−5)×8(−5)−(−7)
(∵ aman=am−n)
=5−2×82=8252=6425
ii)(25)2×7383×7
(25)2×7383×7
= (25×2)×73(23)3×7
(∵(am)n=am×n)
= 210×7329×7
=210−9×73−1=2×72
=2×49=98
:
Formula: 1 Mark
Steps: 2 Marks
Answer: 1 Mark
Given that,
abc=1
So, c=1÷ab=(ab)−1
Similarly,
a=(bc)−1
b=(ac)−1
And,
ab=c−1
ac=b−1
bc=a−1
11+a+b−1+11+b+c−1+11+c+a−1
=11+a+b−1+b−1b−1+bb−1+b−1c−1+aa+ac+aa−1
[Multiplying 2nd term by b−1b−1 and 3rd term by aa]
=11+a+b−1+b−1b−1+1+a+aa+b−1+1
∵ aman=am−n
=1+b−1+a1+a+b−1
=1