Question

Evaluate. (a−2b)3 when a=−3 and b=−1/2 Enter your answer in the box.

Answer 1

Answer:

$-3.5$

Step-by-step explanation:

$(a-2b)^{3} \\=a^{3}-6a^{2} b+6ab^{2}-8b^{3}$

Given that,

$a=(-3)\\b=(-1/2)$

So,

$(a-2b)^{3} \\=a^{3}-6a^{2} b+6ab^{2}-8b^{3}\\=(-3)^{3}-6* (-3)^{2} *\frac{-1}{2} +6*(-3)*(\frac{-1}{2} )^{2} -8*(\frac{-1}{2} )^{3} \\= (-27)-6*9*\frac{-1}{2} +-18*\frac{1}{4} -8*\frac{-1}{8} \\=(-27)-6*-4.5-4.5+1\\=-27+27-4.5+1\\=-3.5$

Hope this helps you

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Answer 2

Answer:

Correct option is

B

(1−3a−3b)(1+a+b)

1−2a−2b−3(a+b)

2

=−3(a+b)

2

−2(a+b)+1

=−3(a+b)

2

−3(a+b)+(a+b)+1

=−3(a+b)((a+b)+1)+((a+b)+1)

=((a+b)+1)(1−3(a+b))

=(a+b+1)(1−3a−3b)