1. ## Sanity check

1. If you re-arrange

$\displaystyle a = \frac {3 + b} {2}$

to make b the subject you get

$\displaystyle b = 3 - 2a$

Yes?
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2. Also, Mulitplying out

$\displaystyle (x + 1)(2x - 3)$

gives

$\displaystyle 2x^2 - 3x - 3$

I'm having a slow morning, are these correct?
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3. Sim Equations

If you have

$\displaystyle x + y = 4$
$\displaystyle 3x + 5y = 22$

I make $\displaystyle x = -1$ and $\displaystyle y = 5$

Is that correct?

1. If you re-arrange

$\displaystyle a = \frac {3 + b} {2}$

to make b the subject you get

$\displaystyle b = 3 - 2a$

Yes? ........ No
_____________________________________
2. Also, Mulitplying out

$\displaystyle (x + 1)(2x - 3)$

gives

$\displaystyle 2x^2 - 3x - 3$ ........ No

I'm having a slow morning, are these correct?
______________________________________
3. Sim Equations

If you have

$\displaystyle x + y = 4$
$\displaystyle 3x + 5y = 22$

I make $\displaystyle x = -1$ and $\displaystyle y = 5$

Is that correct? ........ Yes
$\displaystyle a = \frac {3 + b} {2}~\implies~2a=3+b~\implies~2a-3=b$

$\displaystyle (x + 1)(2x - 3) = 2x^2-3x+2x-3 = 2x^2-x-3$