Here are the solutions to the multiplication of surds problems:
1) 12 × 8 \sqrt{12} \times \sqrt{8} 12 × 8
Step 1: Simplify each surd.
12 = 4 × 3 = 2 3 \sqrt{12} = \sqrt{4 \times 3} = 2\sqrt{3} 12 = 4 × 3 = 2 3
8 = 4 × 2 = 2 2 \sqrt{8} = \sqrt{4 \times 2} = 2\sqrt{2} 8 = 4 × 2 = 2 2
Step 2: Multiply the simplified surds.
2 3 × 2 2 = ( 2 × 2 ) × ( 3 × 2 ) = 4 3 × 2 = 4 6 2\sqrt{3} \times 2\sqrt{2} = (2 \times 2) \times (\sqrt{3} \times \sqrt{2}) = 4\sqrt{3 \times 2} = 4\sqrt{6} 2 3 × 2 2 = ( 2 × 2 ) × ( 3 × 2 ) = 4 3 × 2 = 4 6
2) 45 × 27 \sqrt{45} \times \sqrt{27} 45 × 27
Step 1: Simplify each surd.
45 = 9 × 5 = 3 5 \sqrt{45} = \sqrt{9 \times 5} = 3\sqrt{5} 45 = 9 × 5 = 3 5
27 = 9 × 3 = 3 3 \sqrt{27} = \sqrt{9 \times 3} = 3\sqrt{3} 27 = 9 × 3 = 3 3
Step 2: Multiply the simplified surds.
3 5 × 3 3 = ( 3 × 3 ) × ( 5 × 3 ) = 9 5 × 3 = 9 15 3\sqrt{5} \times 3\sqrt{3} = (3 \times 3) \times (\sqrt{5} \times \sqrt{3}) = 9\sqrt{5 \times 3} = 9\sqrt{15} 3 5 × 3 3 = ( 3 × 3 ) × ( 5 × 3 ) = 9 5 × 3 = 9 15
3) 28 × 8 × 12 \sqrt{28} \times \sqrt{8} \times \sqrt{12} 28 × 8 × 12
Step 1: Simplify each surd.
28 = 4 × 7 = 2 7 \sqrt{28} = \sqrt{4 \times 7} = 2\sqrt{7} 28 = 4 × 7 = 2 7
8 = 4 × 2 = 2 2 \sqrt{8} = \sqrt{4 \times 2} = 2\sqrt{2} 8 = 4 × 2 = 2 2
12 = 4 × 3 = 2 3 \sqrt{12} = \sqrt{4 \times 3} = 2\sqrt{3} 12 = 4 × 3 = 2 3
Step 2: Multiply the simplified surds.
2 7 × 2 2 × 2 3 = ( 2 × 2 × 2 ) × ( 7 × 2 × 3 ) = 8 7 × 2 × 3 = 8 42 2\sqrt{7} \times 2\sqrt{2} \times 2\sqrt{3} = (2 \times 2 \times 2) \times (\sqrt{7} \times \sqrt{2} \times \sqrt{3}) = 8\sqrt{7 \times 2 \times 3} = 8\sqrt{42} 2 7 × 2 2 × 2 3 = ( 2 × 2 × 2 ) × ( 7 × 2 × 3 ) = 8 7 × 2 × 3 = 8 42
4) 8 × 45 × 90 \sqrt{8} \times \sqrt{45} \times \sqrt{90} 8 × 45 × 90
Step 1: Simplify each surd.
8 = 4 × 2 = 2 2 \sqrt{8} = \sqrt{4 \times 2} = 2\sqrt{2} 8 = 4 × 2 = 2 2
45 = 9 × 5 = 3 5 \sqrt{45} = \sqrt{9 \times 5} = 3\sqrt{5} 45 = 9 × 5 = 3 5
90 = 9 × 10 = 3 10 \sqrt{90} = \sqrt{9 \times 10} = 3\sqrt{10} 90 = 9 × 10 = 3 10
Step 2: Multiply the simplified surds.
2 2 × 3 5 × 3 10 = ( 2 × 3 × 3 ) × ( 2 × 5 × 10 ) 2\sqrt{2} \times 3\sqrt{5} \times 3\sqrt{10} = (2 \times 3 \times 3) \times (\sqrt{2} \times \sqrt{5} \times \sqrt{10}) 2 2 × 3 5 × 3 10 = ( 2 × 3 × 3 ) × ( 2 × 5 × 10 )
= 18 × 2 × 5 × 10 = 18 × 100 = 18 × 10 = 180 = 18 \times \sqrt{2 \times 5 \times 10} = 18 \times \sqrt{100} = 18 \times 10 = \boxed{180} = 18 × 2 × 5 × 10 = 18 × 100 = 18 × 10 = 180
5) 12 × 3 20 × 2 45 \sqrt{12} \times 3\sqrt{20} \times 2\sqrt{45} 12 × 3 20 × 2 45
Step 1: Simplify each surd.
12 = 4 × 3 = 2 3 \sqrt{12} = \sqrt{4 \times 3} = 2\sqrt{3} 12 = 4 × 3 = 2 3
3 20 = 3 4 × 5 = 3 × 2 5 = 6 5 3\sqrt{20} = 3\sqrt{4 \times 5} = 3 \times 2\sqrt{5} = 6\sqrt{5} 3 20 = 3 4 × 5 = 3 × 2 5 = 6 5
2 45 = 2 9 × 5 = 2 × 3 5 = 6 5 2\sqrt{45} = 2\sqrt{9 \times 5} = 2 \times 3\sqrt{5} = 6\sqrt{5} 2 45 = 2 9 × 5 = 2 × 3 5 = 6 5
Step 2: Multiply the simplified terms.
2 3 × 6 5 × 6 5 = ( 2 × 6 × 6 ) × ( 3 × 5 × 5 ) 2\sqrt{3} \times 6\sqrt{5} \times 6\sqrt{5} = (2 \times 6 \times 6) \times (\sqrt{3} \times \sqrt{5} \times \sqrt{5}) 2 3 × 6 5 × 6 5 = ( 2 × 6 × 6 ) × ( 3 × 5 × 5 )
= 72 × ( 3 × 5 ) = 72 × 5 3 = 360 3 = 72 \times (\sqrt{3} \times 5) = 72 \times 5\sqrt{3} = 360\sqrt{3} = 72 × ( 3 × 5 ) = 72 × 5 3 = 360 3
6) ( 2 3 ) 2 (2\sqrt{3})^2 ( 2 3 ) 2
Step 1: Apply the exponent to both parts of the term.
( 2 3 ) 2 = 2 2 × ( 3 ) 2 (2\sqrt{3})^2 = 2^2 \times (\sqrt{3})^2 ( 2 3 ) 2 = 2 2 × ( 3 ) 2
Step 2: Calculate the squares and multiply.
4 × 3 = 12 4 \times 3 = \boxed{12} 4 × 3 = 12
7) ( 2 3 ) 2 × ( 2 2 ) (2\sqrt{3})^2 \times (2\sqrt{2}) ( 2 3 ) 2 × ( 2 2 )
Step 1: Calculate ( 2 3 ) 2 (2\sqrt{3})^2 ( 2 3 ) 2 .
( 2 3 ) 2 = 2 2 × ( 3 ) 2 = 4 × 3 = 12 (2\sqrt{3})^2 = 2^2 \times (\sqrt{3})^2 = 4 \times 3 = 12 ( 2 3 ) 2 = 2 2 × ( 3 ) 2 = 4 × 3 = 12
Step 2: Multiply this result by 2 2 2\sqrt{2} 2 2 .
12 × 2 2 = ( 12 × 2 ) 2 = 24 2 12 \times 2\sqrt{2} = (12 \times 2)\sqrt{2} = 24\sqrt{2} 12 × 2 2 = ( 12 × 2 ) 2 = 24 2
That's 2 down. 3 left today — send the next one.