Rewriting complex numbers Practice Questions (Grade 11)

Rewriting complex numbers. Game on.

Rewriting complex numbers is a grade 11 math skill aligned to Common Core standard HSN.CN.A.2: use the relation i² = −1 and the commutative, associative, and distributive properties to add, subtract, and multiply complex numbers. Below are 8 practice questions with answers and step-by-step explanations, drawn from the 10 rewriting complex numbers problems our math games drill.

CCSS HSN.CN.A.210 questions in the bank

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Warm-upeasy

Given $i = \sqrt{-1}$ , what is $\sqrt{49} + \sqrt{-4}$ ?

$\sqrt{49} = 7$ and $\sqrt{-4} = 2i$ . So $\sqrt{49} + \sqrt{-4} = 7 + 2i$ .

Mid-gameeasy

Given $i = \sqrt{-1}$ , what is $\sqrt{81} + \sqrt{-25}$ ?

$\sqrt{81} = 9$ and $\sqrt{-25} = 5i$ . So $\sqrt{81} + \sqrt{-25} = 9 + 5i$ .

Mid-gameeasy

Given $i = \sqrt{-1}$ , what is $\sqrt{4} + \sqrt{-16}$ ?

$\sqrt{4} = 2$ and $\sqrt{-16} = 4i$ . So $\sqrt{4} + \sqrt{-16} = 2 + 4i$ .

Mid-gameeasy

Given $i = \sqrt{-1}$ , what is $\sqrt{64} + \sqrt{-1}$ ?

$\sqrt{64} = 8$ and $\sqrt{-1} = i$ . So $\sqrt{64} + \sqrt{-1} = 8 + i$ .

Mid-gameeasy

Given $i = \sqrt{-1}$ , what is $\sqrt{100} + \sqrt{-49}$ ?

$\sqrt{100} = 10$ and $\sqrt{-49} = 7i$ . So $\sqrt{100} + \sqrt{-49} = 10 + 7i$ .

Mid-gamemedium

Given $i = \sqrt{-1}$ , what is $\sqrt{36} + \sqrt{-81}$ ?

$\sqrt{36} = 6$ and $\sqrt{-81} = 9i$ . So $\sqrt{36} + \sqrt{-81} = 6 + 9i$ .

Mid-gamemedium

Given $i = \sqrt{-1}$ , what is $\sqrt{49} - \sqrt{-16}$ ?

$\sqrt{49} = 7$ and $\sqrt{-16} = 4i$ . So $\sqrt{49} - \sqrt{-16} = 7 - 4i$ .

Buzzer beatermedium

Given $i = \sqrt{-1}$ , what is $\sqrt{121} - \sqrt{-9}$ ?

$\sqrt{121} = 11$ and $\sqrt{-9} = 3i$ . So $\sqrt{121} - \sqrt{-9} = 11 - 3i$ .

Rewriting complex numbers. Game on.

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