Question

Помогите пж решить все

Answer 1

$\displaystyle\bf\\1)\\\\(4x^{2} -4x+7)-(2x^{2} -3x+5)=\\\\=4x^{2} -4x+7-2x^{2} +3x-5=\\\\=(4x^{2} -2x^{2} )+(3x-4x)+(7-5)=\\\\=2x^{2} -x+2\\\\2)\\\\(2ab-5c)+(3a^{2} b+3c)=2ab-5c+3a^{2} b+3c=\\\\=3a^{2} b+2ab+(3c-5c)=3a^{2} b+2ab-2c\\\\3)\\\\4(2x+4y)-3(x-3y)+7=8x+16y-3x+9y+7=\\\\=5x+25y+7\\\\x=2 \ \ ; \ \ y=-1\\\\5x+25y+7=5\cdot 2+25\cdot(-1)+7=10-25+7=-8\\\\4)\\\\(3x-5)(2x+7)=3x\cdot 2x+3x\cdot 7-5\cdot 2x-5\cdot 7=\\\\=6x^{2} +21x-10x-35=6x^{2} +11x-35$