EXERCISE 12.3

Simplify the expression $2-8x+4x+4$, and find the value if $x=3$.

Simplify the expression $3a+5-8a+1$, and find the value if $a=-1$.

Simplify the expression $10-3b-4-5b$, and find the value if $b=-2$.

Simplify the expression $2a-2b-4-5+a$, and find the value if $a=-1, b=-2$.

If $z=10,$ find the value of $z^3–3(z-10)$

If $p=-10,$ find the value of $p^2-2p-100$

What should be the value of $a$ if the value of $2x^2+x-a$ equals to $5,$ when $x=0$?

Find the value of the expression $2(a^2+ab)+3-ab$, when $a=5$ and $b=-3$.