Question

rápido preciso das respostas corretas destas três perguntas?

Answer 1

$e) (x-3)(x+5)+6=2x+7\\ \\\\ x^{2} +5x-3x-15+6=2x+7\to\\\\ x^{2} +5x-3x-15+6-2x-7=0\to\\\\ x^{2} +5x-3x-2x -15+6-7=0\to \\\\ x^{2} +5x-5x-15+6-7=0\to \\\\x^{2} -16=0\to\\\\ x^{2} =16\to\\\\ x=+- \sqrt{16}\to \\\\ x=+-4 \\\\\\ S=(-4;4)$






$f) (x+3)(x+2)+3(x+3)=0\\\\ \\ x^{2} +2x+3x+6+3x+9=0\to\\\\ x^{2} +8x+15=0\\\\ a=1;b=8;c=15 \\\\ \Delta=b^2-4ac\to \Delta=8^2-4*1*15\to \Delta=64-60\to \Delta=4\\\\ x= \frac{-b+- \sqrt{\Delta} }{2a} \to x= \frac{-8+- \sqrt{4} }{2*1} \to x= \frac{-8+- 4}{2} \to \\\\ x'= \frac{-8+ 4}{2} \to x'= \frac{-4}{2} \to x'=-2\\\\ x''= \frac{-8- 4}{2} \to x''= \frac{-12}{2} \to x''=-6\\\\\\ S=(-6;-2)$







$g) (x+3)(x+2)-2(x-3)=10\\\\ \\ x^{2} +2x+3x+6-2x+6=10\to \\\\ x^{2} +2x+3x+6-2x+6-10=0\to \\\\ x^{2} +3x+2=0\\\\ a=1;b=3;c=2\\\\ \Delta=b^2-4ac\to \Delta=3^2-4*1*2\to \Delta=9-8\to \Delta=1\\\\ x= \frac{-b+- \sqrt{\Delta} }{2a} \to x= \frac{-3+- \sqrt{1} }{2*1} \to x= \frac{-3+- 1 }{2} \to\\ \\x'= \frac{-3+ 1 }{2} \to x'= \frac{-2 }{2} \to x'=-1\\\\ x'' = \frac{-3- 1 }{2} \to x''= \frac{-4 }{2} \to x''=-2\\\\\\ S=(-2;-1)$



Prontinho , espero ter ajudado...