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CAN SOMEONE SHOW ME HOW TO DO THIS PLEASE????????????????

CAN SOMEONE SHOW ME HOW TO DO THIS PLEASE????????????????-example-1

1 Answer

1 vote

Answer:

see explanation

Explanation:

(s • t)(x) = s(x) × t(x)

= (x + 4)(2x - 5) ← expand using FOIL

= 2x² - 5x + 8x - 20 ← collect like terms

= 2x² + 3x - 20

(s - t)(x) = s(x) - t(x)

= x + 4 - (2x - 5) ← distribute by - 1

= x + 4 - 2x + 5 ← collect like terms

= - x + 9 = 9 - x

(s + t)(x) = s(x) + t(x)

= x + 4 + 2x - 5 = 3x - 1

To evaluate (s + t)(4) substitute x = 4 into (s + t)(x)

= ( 3 × 4) - 1 = 12 - 1 = 11

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