$f(x) = \left\{ \begin{array} {1 1} 5, & \quad\text{ if x_1 \leq x \leq \sqrt 2 } \\ ax+b ,& \quad \text{if $2x$ < 10 }\\ 21 ,& \quad \text{if $x$ \geq 10 } \end{array} \right.$ Find the values of a and b

Question

$\begin{array}{1 1} 1,0 \\ 3,-2 \\2,0 \\ 5,2 \end{array}$