Question #cfc36

2 Answers
Oct 17, 2017

x=1\frac{1}{11}x=1111

Explanation:

\frac{x}{4}=\frac{3}{11}x4=311

You can solve it by using proportion:

x=\frac{4 xx 3}{11}=\frac{12}{11}x=4×311=1211

x=1\frac{1}{11}x=1111

Oct 17, 2017

x=12/11x=1211

Explanation:

Have a look at https://socratic.org/help/symbols for formatting. Note the hash at the beginning and end of the typed text. This triggers the implementation of mathematical formatting.

Given: x/4=3/11x4=311

Our target is to have xx on its own on one side of the equals and all the numbers on the other side

color(red)("First principles method")First principles method

If we can change the 1/414bit from x/4x4 into 1 then x xx1->xx×1x and we have solved it.

Write as

color(green)(x xx1/4=3/11)x×14=311

Multiply both sides by color(red)(4)4

color(green)(x xx1/4color(red)(xx4)color(white)("ddd")=color(white)("ddd")3/11color(red)(xx4))x×14×4ddd=ddd311×4

color(green)(color(white)("dd")x xx(color(red)(4))/4color(white)("dddd")=color(white)("ddd")(3color(red)(xx4))/11)ddx×44dddd=ddd3×411

color(white)("dd")x xx1color(white)("ddddd") =color(white)("ddd")12/11ddx×1ddddd=ddd1211

x=12/11x=1211
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color(red)("Shortcut method ")Shortcut method

color(brown)("Basically this is just remembering what happens with first principles")Basically this is just remembering what happens with first principles

Consider the 4 from x/4x4

This is x-:4x÷4 so move the 4 to the other side of the equals and use the opposite action to divide. Which is multiply.

So x/4=3/11 color(white)("d")->color(white)("d")color(white)("d")x=3/11xx4x4=311dddx=311×4

x=12/11x=1211