If a=2i-3j-k and b=i+4j+2k what us ab

2i²+5ij+3ik-12j²-10jk-2k²

Step-by-step explanation:

a=2i-3j-k

b=i+4j+2k

ab = (2i-3j-k) (i+4j+2k)

Multiply both bracket by expanding the bracket

2i(i+4j+2k)-3j(i+4j+2k)-k(i+4j+2k)

Multiply

2i²+8ij+4ik-3ij-12j²-6jk-ik-4jk-2k²

Collect like terms

2i²+8ij-3ij+4ik-ik-12j²-6jk-4jk-2k²

2i²+5ij+3ik-12j²-10jk-2k²

"standard form:

3x2 + 14x − 10 = 0

solutions based on quadratic formula:

x1   = −14 − √ 142 − 4×3×(−10) /   2×3   = −14 − 2 × √ 79 /   6   ≈ −5.296

x2   = −14 + √ 142 − 4×3×(−10) /   2×3   = −14 + 2 × √ 79 /   6   ≈ 0.629

86

step-by-step explanation:

find the area of the triangle then multiply by 2 then add the area of the parollelegram multiplied by 2