solving quadratic equations by factoring

[preapgirl]

i really need help trying to find solving quadratic equations by factoring:
please show how to do work

** only have to choose one please

questions:

xsquared= 400

-25=xsquared

36=xsquared

0=81xsquared-25

49xsquared+64=0

16xsquared+10=131

0=4xsquared-16

 

[masters]

i really need help trying to find solving quadratic equations by factoring:
please show how to do work

** only have to choose one please

questions:

xsquared= 400

-25=xsquared

36=xsquared

0=81xsquared-25

49xsquared+64=0

16xsquared+10=131

0=4xsquared-16

Hi preapgirl,

[1] $\displaystyle x^2=400$

Transpose the 400 to set equation = 0

$\displaystyle x^2-400=0$

This is the difference of two squares. The model for that is $\displaystyle a^2-b^2=(a-b)(a+b)$

Can you take it from here?

[2] $\displaystyle -25=x^2$

This one's very similar to the first one with one exception.

When you transpose the -25 to set the equation to zero, you end up with the sum of two squares.

$\displaystyle x^2+25=0$

This cannot be factored in the domain of real numbers.

[3] $\displaystyle 36=x^2$

This is like [1]

[4] $\displaystyle 0=81x^2-25$

This is still the difference of two squares: $\displaystyle 81x^2-25=(9x-5)(9x+5)$

Let's see if you can finish up, ok?