Math Is Fun Forum

Stanley_Marsh

Member

Registered: 2006-12-13

Posts: 345

I can't solve this equation

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Numbers are the essence of the Universe

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: I can't solve this equation

Well, I plotted the graphs of y = 1.4[sup]x[/sup] and y = −x[sup]2[/sup]+4x+1 and found two solutions. One of them is x = 0; the other solution lies between x=3 and x=4.

Stanley_Marsh

Member

Registered: 2006-12-13

Posts: 345

Re: I can't solve this equation

Yeah ,  I find it between 3 and 4 too
It's a homework from my friend  , it said , find out and intersection numerically  ( y = 1.4^x , y = −x^2+4x+1 )

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Numbers are the essence of the Universe

Stanley_Marsh

Member

Registered: 2006-12-13

Posts: 345

Re: I can't solve this equation

It's so strange~  I graph the

on my computer , it's like a parabola!!!!!

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Numbers are the essence of the Universe

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: I can't solve this equation

Hi;

Bracket off the roots as Jane has done and use interval bisection to numerically home in. It is inefficient but it is easy to understand.

x ≈ 3.374039462876937034664184 and x = 0

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.