Question

$(3x - 7)^{2} -(10-3x)(2x-5)+11=2(2+1) ^{2} - 7(x-1)(9-x)$

Rezolvare si proba

(Rezultatul de la sfarsitul cartii este x = 3)

Answer 1

(3x-7)²-(10-3x)(2x-5)+11=2(2x+1)²-7(x-1)(9-x)
9x²+49-42x-(20x-50-6x²+15x)+11=2(4x²+4x+1)-7(9x-x²-9+x)
9x²+49-42x-35x+50+6x²+11=8x²+8x+2-63x+7x²+63-7x
15x²+110-77x=15x²-62x+65 (se reduc 15x²)
110-77x=65-62x
110-65=77x-62x
15x=45 x=3
Proba:
(3×3-7)²-(10-3×3)(2×3-5)+11=2(2×3+1)²-7(3-1)(9-3)
(9-7)²-(10-9)×(6-5)+11=2(6+1)²-7(2×6)
2²-1×1+11=2×49-7×12
4-1+11=98-84
14=14

Answer 2

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