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I hate to ask it…. How do we multiply and divide these things?. Before we begin. Remember multiplying binomials? (Binomials are things with two terms) Ex. (x – 2), (y + 7), (3 + 5z) To multiply two binomials, we had to multiply each part of each binomial FOIL First, Outer, Inner, Last.
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I hate to ask it… How do we multiply and divide these things?
Before we begin • Remember multiplying binomials? • (Binomials are things with two terms) • Ex. (x – 2), (y + 7), (3 + 5z) • To multiply two binomials, we had to multiply each part of each binomial • FOIL • First, Outer, Inner, Last
Multiplying binomials • (x+3)(x-5) • Multiply first terms: x*x=x2 • Multiply outer terms: x*(-5)=-5x • Multiply inner terms: 3*x=3x • Multiply last terms: 3*(-5)=-15 • Add them all together: x2-5x+3x-15 • Combine like terms: x2-2x-15
Important cases • Squaring binomial • (x+y)(x+y)=(x+y)2 • =x2+2xy+y2 • Conjugates • (x+y)(x–y)=x2-xy+xy-y2 • x2-y2
Treat complex numbers like binomials, ¡que facil! • (3-6i)*2i • =3*2i–6i*2i • =6i-12i2 • =12+6i • You need to remember to simplify the i and combine like terms!