# Help with Algebra Questions

#### John Robbo

##### New member
I have attempted the questions in the attached sheet could someone check if the answers are correct.

1. + = 1.28
- = -0.69

2. Transposed to

t = ln (P/Po) -5 / 1.2

t= -3.18

3. x = 0
x = 2.5

4. t= -0.125
s= 10.7

Thanks

#### Sudharaka

##### Well-known member
MHB Math Helper
I have attempted the questions in the attached sheet could someone check if the answers are correct.

View attachment 1985

1. + = 1.28
- = -0.69

2. Transposed to

t = ln (P/Po) -5 / 1.2

t= -3.18

3. x = 0
x = 2.5

4. t= -0.125
s= 10.7

Thanks
Hi John Robbo,

Welcome to MHB!

The first and third and fourth answers are correct. For the fourth answer I get $$t=-0.127$$ when rounded to three decimal places.

In the third answer you have messed up with a minus sign.

$p=p_0 e^{5-1.2t}$

$\Rightarrow \ln\left(\frac{p}{p_0}\right)=5-1.2t$

$\Rightarrow t=\frac{1}{1.2}\left(5-\ln\left(\frac{p}{p_0}\right)\right)$

which gives you, $t=3.18$.

#### John Robbo

##### New member
sudharaka thanks for your help understand where I went wrong

#### Sudharaka

##### Well-known member
MHB Math Helper
sudharaka thanks for your help understand where I went wrong
You are welcome.