Question
(i) Will the value of 2x2+12x+3 for x = - 4 be greater than or less than 15?
(ii) If x2 is added to 2x2+12x+3 and 15 is subtracted from it then evaluate its value at x = -4? [3 MARKS]
(ii) If x2 is added to 2x2+12x+3 and 15 is subtracted from it then evaluate its value at x = -4? [3 MARKS]
Answer:
:
Each part: 1.5 Marks
(i) Value of the expression for x=−4
2x2+12x+3
2(−4)2+12(−4)+3
2(16)−48+3
32−48+3=−15
Hence, the value of expression 2x2+12x+3 at x=−4 is lesser than 15.
(ii) As per question
x2 is added to 2x2+12x+3 and 15 is subtracted from it
So, the final expression is:
2x2+12x+3+x2−15
3x2+12x−12
On putting x = -4 in the above equation we get:
3×(−4)2+12×(−4)−12
=48−48−12
=−12
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:
Each part: 1.5 Marks
(i) Value of the expression for x=−4
2x2+12x+3
2(−4)2+12(−4)+3
2(16)−48+3
32−48+3=−15
Hence, the value of expression 2x2+12x+3 at x=−4 is lesser than 15.
(ii) As per question
x2 is added to 2x2+12x+3 and 15 is subtracted from it
So, the final expression is:
2x2+12x+3+x2−15
3x2+12x−12
On putting x = -4 in the above equation we get:
3×(−4)2+12×(−4)−12
=48−48−12
=−12
Was this answer helpful ?
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