a) E(x)=4x²+12x+9-8x+2x²+4-x-2x²-8x-8+3x-2
E(x)=4x²-2x+3, pentru orice număr real x.
b) 4n²-2n+3≤2n+8+3
4n²-2n+3≤2n+11 |-3
4n²-2n≤2n+8
4n²-2n-2n-8≤0
4n²-4n-8≤0 |÷4
n²-n-2≤0
n²+n-2n-2≤0
n(n+1)-2(n+1)≤0
(n-2)(n+1)≤0
n-2≤0 -> n≤2
n+1≥0 -> n≥-1
n-2≥0 -> n≥2
n+1≤0 -> n≤-1
-> n={-1; 0; 1; 2}
Răspuns:
Explicație pas cu pas:
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a) E(x)=4x²+12x+9-8x+2x²+4-x-2x²-8x-8+3x-2
E(x)=4x²-2x+3, pentru orice număr real x.
b) 4n²-2n+3≤2n+8+3
4n²-2n+3≤2n+11 |-3
4n²-2n≤2n+8
4n²-2n-2n-8≤0
4n²-4n-8≤0 |÷4
n²-n-2≤0
n²+n-2n-2≤0
n(n+1)-2(n+1)≤0
(n-2)(n+1)≤0
n-2≤0 -> n≤2
n+1≥0 -> n≥-1
n-2≥0 -> n≥2
n+1≤0 -> n≤-1
-> n={-1; 0; 1; 2}
Răspuns:
Explicație pas cu pas: