# Warm-Up (Over 4.5) [1]Evaluate Calculator Free: [2]Find the area of a triangle whose vertices are at (9, 0) (-3, 10) and (5, -6).

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Warm-Up (Over 4.5) [1]Evaluate Calculator Free: [2]Find the area of a triangle whose vertices are at (9, 0) (-3, 10) and (5, -6).

Warm-Up (Chapter 4 RV) [1] [2] [3]Jim invested \$3000 into three 3 accounts at 5%, 8%, and 10% respectively. After one year the interest gained was \$255. If the he invested \$500 more in the 8% than the 5% how much did he invest in each? (-3.8, 1.4) X + Y + Z = 3000 X = 5% Y = 8% Z = 10%.05X +.08Y +.10Z = 255 Y = X + 500 X = \$500 Y = \$1000 Z = \$1500

Lesson 4.7Identity and Inverse Matrices 2 x 2 Identity 3 x 3 Identity Identity Property of Multiplication: Inverse Property of Multiplication: If the product of two matrices is an identity matrix, then the two matrices are inverses. (Not all matrices have an inverse)

Finding Inverse of a 2x2 Matrix Where ad-bc does not equal 0. If determinant (ad-bc) =0 then no inverse. NOTE: the value of ad-bc is the determinant of A

Practice finding the Inverse (by hand) 1. 3. 2. 4.

Example 1Finding an Inverse (Calculator Active) Note:Not all matrices have an inverse. A SINGULAR MATRIX error message entails there is no inverse. a) b)

Example 2Verifying Inverses (Calculator Active) a) b)

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