Answer:
Step-by-step explanation:
1) f(x) = 7 - 8x²
f(3) = 7 - 8*3²
= 7 - 8*9
= 7 - 72
f(3) = -65
2) f(a) = -5(a-2)
f(3) = -5(3 -2) = -5 * 1 = -5
4) f(m) = m(m +4)
f(3) = 3*(3+4) = 3 * 7 = 21
6(√2 - 5√3).
3√2 ( 2 - 5 √6)
= 6√2 - 15√12
= 6√2 - 15√4√3
= 6√2 - 30√3
= 6(√2 - 5√3)