Substitution

If $x=4$, evaluate: $-4x^{2}-6x-9$

If $x=-4$, evaluate: $2x^{2}-6x-9$

If $x=80$, evaluate: $\sqrt{5x}$

If $x=3$ and $y=3$, evaluate: (4x + 12) / (4y − 16)

If $x=4$ and $y=3$, evaluate: (5x − 62) / (4y − 6)

If $x=-3$, evaluate: $4x+13$

If $x=2$, evaluate: $3x-15$

If $x=6$, evaluate: $8x+6$

If $x=-2$, evaluate: $6x^{2}-5x-12$

If $x=-5$, evaluate: $7x-11$

If $x=-4$, evaluate: $2x^{2}+4x-7$

If $x=128$, evaluate: $\sqrt{8x}$