# 75^40=9^20*5^x

can anyone tell me how to solve this. Note by Daniel Kua
6 years, 5 months ago

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## Comments

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Which one do you mean I or II :

• $75^{40} = 9^{20 \times 5^{x}} . . . . . I$

• $75^{40} = 9^{20} \times 5^{x} . . . . .II$

- 6 years, 5 months ago

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no.2

- 6 years, 5 months ago

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how do u type multiple again? tell me pls.

- 6 years, 5 months ago

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You can see how to type in math formatting by click on "formatting guide" at the bottom-left corner of your comment box.

To type multiple, just type " \times " in math format (remember, in math format! See how to start a math format in the formatting guide.

The more easy ways to know the format of symbols, just point your cursor at the symbols, the format then will appears.

- 6 years, 5 months ago

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the 2nd one

- 6 years, 5 months ago

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Sorry for the late response,

$75^{40} = 9^{20} \times 5^{x}$

$75^{40} = (3^2)^{20} \times 5^{x}$

$75^{40} = 3^{40} \times 5^{x}$

$\frac{75^{40}}{3^{40}} = 5^{x}$

$(\frac{75}{3})^{40} = 5^{x}$

$25^{40} = 5^{x}$

$(5^2)^{40} = 5^{x}$

$5^{80} = 5^{x}$

$\boxed{x = 80}$

- 6 years, 5 months ago

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$75^{40}= (3*25)^{40}$

$= 3^{40} * 25^{40}$

$= 3^{2*20} * (5^2)^{40}$

$= (3^2)^{20} * 5^{2*40}$

$= 9^{20}*5^{80}$

Therefore $x = 80$. I only used 2 formulae, $(ab)^n = a^n * b^n$ and $(a^n)^m = a^{m*n}$

Also, to write all the signs, read this

- 6 years, 5 months ago

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3^40 is not equal to 3^20+2

- 6 years, 4 months ago

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Of course not. Look at this exponent's formulas :

$a^x \times a^y = a^{x+y}$

$(a^x)^y = a^{xy}$

So,

$3^{40} \neq 3^{20+2}$ but

$3^{40} = 3^{2 \times 20} = (3^2)^{20}$

Got it?

- 6 years, 4 months ago

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Its $3^{20 \times 2}$. I used the $*$ symbol.

- 6 years, 4 months ago

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x=80

- 6 years, 4 months ago

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X=80

- 6 years, 2 months ago

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