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# In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by

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Joined: 02 Sep 2009
Posts: 58434
In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by  [#permalink]

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12 Mar 2018, 21:59
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In the formula $$a=b^2c$$, if b is multiplied by 2 and c is multiplied by 3, then $$a$$ must be multiplied by

A. 4
B. 6
C. 9
D. 12
E. 18

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Math Expert
Joined: 02 Sep 2009
Posts: 58434
Re: In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by  [#permalink]

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12 Mar 2018, 22:02
Bunuel wrote:
In the formula $$a=b^2c$$, if b is multiplied by 2 and c is multiplied by 3, then $$a$$ must be multiplied by

A. 4
B. 6
C. 9
D. 12
E. 18

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Re: In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by  [#permalink]

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13 Mar 2018, 05:02
Bunuel wrote:
In the formula $$a=b^2c$$, if b is multiplied by 2 and c is multiplied by 3, then $$a$$ must be multiplied by

A. 4
B. 6
C. 9
D. 12
E. 18

$$a=b^2c$$

if b is multiplied by 2 and c is multiplied by 3,

$$a_new=(2b)^2(3c)$$

$$a_new=12(b)^2(c)$$

i.e. a Must be multiples by 12

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Re: In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by  [#permalink]

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13 Mar 2018, 07:45
Bunuel wrote:
In the formula $$a=b^2c$$, if b is multiplied by 2 and c is multiplied by 3, then $$a$$ must be multiplied by

A. 4
B. 6
C. 9
D. 12
E. 18

Plug in b = 2 and c = 3

So, $$a = b^2c$$ , ie $$a = 2^2*3$$

Hence, answer must be (D) 12
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In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by  [#permalink]

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13 Mar 2018, 23:54
Bunuel wrote:
In the formula $$a=b^2c$$, if b is multiplied by 2 and c is multiplied by 3, then $$a$$ must be multiplied by

A. 4
B. 6
C. 9
D. 12
E. 18

a = b^2

Multiplying b by 2 we get 2b

Multiplying c by 3 we get 3c

Now, a = (2b)^2 * 3c

a = 12b^2 * c

a needs to be multiplied by 12 (D).
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Re: In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by  [#permalink]

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14 Mar 2018, 16:01
Bunuel wrote:
In the formula $$a=b^2c$$, if b is multiplied by 2 and c is multiplied by 3, then $$a$$ must be multiplied by

A. 4
B. 6
C. 9
D. 12
E. 18

If b is multiplied by 2 and c is multiplied by 3, then we will have (2b)^2 * (3c) = 12b^2 * c, which is 12 times its original value. Since the right hand of the original equation has increased by a factor of 12, we must multiply the left side of the equation by 12 as well.

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In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by  [#permalink]

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19 Mar 2018, 11:35

SOLUTION

We are given:
• $$a$$= $$b^2$$ c

If we multiply $$b$$ by $$2$$ and $$c$$ by $$3$$, then $$b$$ becomes $$2b$$ and $$c$$ becomes $$3c$$.
Thus, the new value of $$a$$ is equal to:

• =$$(2b)^2$$ *$$(3c)$$
• =$$4*$$$$b^2$$*$$3*c$$
• = $$12$$* ($$b^2$$ *$$c$$)
• =$$12*a$$
Therefore, $$a$$ must be multiplied by $$12$$.

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In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by   [#permalink] 19 Mar 2018, 11:35
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# In the formula a=b^2c, if b is multiplied by 2 and c is multiplied by

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