Quad polynomials help (1 Viewer)

Munkiie · Mar 30, 2013

I need help with these questions

1) find values of m such that mx^2 + 3x -4 <0 for all x

2) solve 5^2x - 26.5^x +25=0

Thanks in advance

TimeGoesTooFast · Mar 30, 2013

I'll just give you hints.
1) Use discriminant, which has to be less than 0 such that it has no roots.
2) let X= 5^x (it's reducible quadratics)- Solve 5X^2-26X+25=0

TheMathStudent · Mar 31, 2013

^Think you meant to say $x^2-26x+25$ not 5x^2

TimeGoesTooFast · Mar 31, 2013

yeah my bad, was in a rush.

asianese · Mar 31, 2013

I think 2) was actually

$5^{2x}-26 \cdot 5^x+25=0$ . To solve this, let $u=5^x$ so that the equation becomes $u^2-26u+25=0$ since $5^{2x} = 5^{2\times x} = (5^x)^2$

SharkeyBoy · Mar 31, 2013

therefore (u-25)(u-1)=0
u = 25,1
5^x = u
x = 0,2

Quad polynomials help (1 Viewer)

Munkiie

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TimeGoesTooFast

Mapler

TheMathStudent

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TimeGoesTooFast

Mapler

asianese

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SharkeyBoy

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