Răspuns:
Explicație:
E(x)=(5x+3)²+(10x+6)(3x-7)+(3x-7)²
a. E(x)=25x²+30x+9+30x²-70x+18x-42+9x²-42x+49
E(x)=64x²-64x+16= 16(4x²-4x+1)=16(2x-1)²
E(-2)=16(16+9)=16×25=20² este patrat perfect
b. [tex]\frac{1}{8}[/tex]×16(2x-1)²-8x²=10
2(4x²-4x+1)-8x²=10 |:2
4x²-4x+1-4x²=5
-4x+1=5
-4x=4
x=-1