Answer:
1. x² - 5x + 4
x = 1
(1)² - 5(1) + 4
1 - 5 + 4
-4 + 4
2. 2y² - y - 6
y = -2
2(-2)² - (-2) - 6
2(4) + 2 - 6
8 + 2 - 6
10 - 6
3. x³ - 6x² + 12x - 15
x = 2
(2)³ - 6(2)² + 12(2) - 15
8 - 6(4) + 24 - 15
8 - 24 + 24 - 15
8 - 15
4. 3z^7 - z² + 4z - 1
z = -1
3(-1)^7 - (-1)² + 4(-1) - 1
3(-1) - 1 - 4 - 1
-3 - 1 - 4 - 1
-4 - 4 - 1
-8 - 1
5. 8x³ - 2x + 5
x = 1/2
8(1/2)³ - 2(1/2) + 5
8(1/8) - 1 + 5
1 - 1 + 5
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Verified answer
Answer:
1. x² - 5x + 4
x = 1
(1)² - 5(1) + 4
1 - 5 + 4
-4 + 4
= 0
2. 2y² - y - 6
y = -2
2(-2)² - (-2) - 6
2(4) + 2 - 6
8 + 2 - 6
10 - 6
= 4
3. x³ - 6x² + 12x - 15
x = 2
(2)³ - 6(2)² + 12(2) - 15
8 - 6(4) + 24 - 15
8 - 24 + 24 - 15
8 - 15
= -7
4. 3z^7 - z² + 4z - 1
z = -1
3(-1)^7 - (-1)² + 4(-1) - 1
3(-1) - 1 - 4 - 1
-3 - 1 - 4 - 1
-4 - 4 - 1
-8 - 1
= -9
5. 8x³ - 2x + 5
x = 1/2
8(1/2)³ - 2(1/2) + 5
8(1/8) - 1 + 5
1 - 1 + 5
= 5