Find an equation of the line described below. Write the equation in​ slope-inter

Find a least squares solution of Ax=b by constructing and solving the normal equations.
${\displaystyle A=\left[\begin{array}{cc}3& 1\\ 1& 1\\ 1& 4\end{array}\right],b\left[\begin{array}{c}1\\ 1\\ 1\end{array}\right]}$
${\displaystyle \bar{x}=}$?

What is the solution to this system of equations?
3x-y+5=0
2x+3y-4=0

Solve the equation.
${\displaystyle 3^{x^2-4}={27}^x}$

What did happened to number +1

Determine whether the given problem is an equation or an expression. If it is an equation, then solve. If it is an expression, then simplify. ${\displaystyle \frac{2}{5}(x+4)+\frac{1}{3}(x-2)}$

Solve the equation.
${\displaystyle \frac{7}{y^2-4}-\frac{4}{y+2}=\frac{5}{y-2}}$

Write an equation to solve each problem. Two brothers are saving money to buy tickets to a concert. Their combined savings is $\mathrm{\$}55$. One brother ha s $\mathrm{\$}15$ more than the other. How much has each saved?