Algebra 2

Algebra Level 1

How many times do the graphs of y = x y\quad =\quad x and y = x 2 y\quad =\quad { x }^{ 2 } intersect?


The answer is 2.

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1 solution

Dominick Hing
Sep 28, 2014

You can set the equations equal to each other so that

x = x 2 x\quad =\quad { x }^{ 2 }

since they are both equal to y. Do not divide both sides by x. Instead, subtract x from both sides and factor to get

0 = x ( x 1 ) 0\quad =\quad { x }(x-1) .

There are two possible solutions: 0 and 1. Thus, the two graphs intersect twice. If you divided both sides by x in the previous steps, you would have lost the 0 since you would have gotten

x x = x 2 x \frac { x }{ x } \quad =\quad \frac { { x }^{ 2 } }{ x }

and then

1 = x 1=x

if we just divide it by x, we have only one solution for that..

Andro Dellosa - 6 years, 8 months ago

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