Question

Evaluate the expressions given below for a= -4.
7a2 + 7a - 20
a3 + 2a2 - a + 5
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Answer 1

Answer:

i) 64,

ii) -23

Step-by-step explanation:

If a = -4 ,

then

i) Value of 7a²+7a-20

= 7(-4)²+7(-4)-20

= 7×16-28-20

= 112 - 48

= 64

ii) Value of a³+2a²-a+5

= (-4)³+2(-4)²-(-4)+5

= -64+2×16+4+5

= -64+32+9

= -64 + 41

= -23

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Answer 2

Answer:

Step-by-step explanation:

a = -4 ( given )

7a^2 + 7a - 20

putting the value of a

7 x -4 x -4 + 7 x - 4 - 20

112 - 28 - 20

= 64

a^3 + 2a^2 - a + 5

putting the value of a

-4 x -4 x -4 + 2 x -4 x -4 + 4 + 5

-64 + 32 + 9

-32 + 9

= -23