# How to solve for x?

• Sep 12th 2009, 05:28 PM
loutja35
How to solve for x?
How would you solve for x? For some reason I just can't figure them out... I greatly appreciate anyone who could help me :)

#1) y= √x
y = x^2

#2) y=e^-x
y=e^x

#3) y=4-x^2
y=1-x^2

#4)
y=e^x
y=ex

#5) y=x^3-3x+1
x+y
• Sep 12th 2009, 06:15 PM
Quote:

Originally Posted by loutja35
How would you solve for x? For some reason I just can't figure them out... I greatly appreciate anyone who could help me :)

#1) y= √x
y = x^2

#2) y=e^-x
y=e^x

#3) y=4-x^2
y=1-x^2

#4)
y=e^x
y=ex

#5) y=x^3-3x+1
x+y

Hi

(1) \$\displaystyle y^2=x\$ ---1 (square both sides)

\$\displaystyle y=x^2 \$---2

sub 2 into 1

\$\displaystyle (x^2)^2=x \$

\$\displaystyle
x^4=x
\$

\$\displaystyle x^4-x=0\$ .... continue here

(2) \$\displaystyle y^x=e\$ --1

\$\displaystyle y=e^x\$ ---2

sub 2 into 1

\$\displaystyle (e^x)^x=e \$

\$\displaystyle e^{2x}=e \$

continue here

Can you try the rest ?
• Sep 13th 2009, 06:39 AM
loutja35
Although you said continue here and I can see your process....I don't know how to continue forward. It looks to me like x isn't being solved for. I don't understand what I am doing wrong. Please help...thank you to anyone who can
• Sep 13th 2009, 07:23 AM
stapel
1) Factor. Apply the difference-of-cubes formula to x^3 - 1. Solve the two linear factors.

2) To learn how to solve exponential equations, try here. (Wink)