Câu hỏi của Ngân Hanna

Question

Rút gọn

E=(4-x)(x+4)-(x+2)²

P=(2x+3)²-(2x+1)(2x-1)

Q=(4-3x)²-(9x-1)(9x+1)

M=(5+x) (x-5)-(x-3)²

N=2(3x+1)(x-2)-6(x+2)²

Nguyễn Thị Huyền Trang · Accepted Answer

+) $E=\left(4-x\right)\left(x+4\right)-\left(x+2\right)^2=16-x^2-x^2-4x-4$

$=-2x^2-4x+12$

+)$P=\left(2x+3\right)^2-\left(2x+1\right)\left(2x-1\right)=4x^2+12x+9-4x^2+1$

$=12x+10$

+)$Q=\left(4-3x\right)^2-\left(9x-1\right)\left(9x+1\right)=16-24x+9x^2-81x^2+1$

$=-72x^2-24x+17$

+) $M=\left(5+x\right)\left(x-5\right)-\left(x-3\right)^2=x^2-25-x^2+6x-9$

$=6x-34$

+) $N=2\left(3x+1\right)\left(x-2\right)-6\left(x+2\right)^2=\left(6x+2\right)\left(x-2\right)-6\left(x^2+4x+4\right)$

$=6x^2-12x+2x-4-6x^2-24x-24=-34x-28$Câu trả lời: +) $E=\left(4-x\right)\left(x+4\right)-\left(x+2\right)^2=16-x^2-x^2-4x-4$

$=-2x^2-4x+12$

+)$P=\left(2x+3\right)^2-\left(2x+1\right)\left(2x-1\right)=4x^2+12x+9-4x^2+1$

$=12x+10$

+)$Q=\left(4-3x\right)^2-\left(9x-1\right)\left(9x+1\right)=16-24x+9x^2-81x^2+1$

$=-72x^2-24x+17$

+) $M=\left(5+x\right)\left(x-5\right)-\left(x-3\right)^2=x^2-25-x^2+6x-9$

$=6x-34$

+) $N=2\left(3x+1\right)\left(x-2\right)-6\left(x+2\right)^2=\left(6x+2\right)\left(x-2\right)-6\left(x^2+4x+4\right)$

$=6x^2-12x+2x-4-6x^2-24x-24=-34x-28$

Mashiro Shiina · Answer

$E=\left(4-x\right)\left(x+4\right)-\left(x+2\right)^2$

$E=4x+16-x^2-4x-x^2-4x-4$

$E=-2x^2-4x+12$

$P=\left(2x+3\right)^2-\left(2x+1\right)\left(2x-1\right)$

$P=4x^2+12x+9-4x^2-1$

$P=12x+10$

$Q=\left(4-3x\right)^2-\left(9x-1\right)\left(9x+1\right)$

$Q=16-24x+9x^2-81x^2+1$

$Q=17-24x-74x^2$

$M=\left(5+x\right)\left(x-5\right)-\left(x-3\right)^2$

$M=5x-25+x^2-5x-x^2+6x-9$

$M=-34+6x$

$N=2\left(3x+1\right)\left(x-2\right)-6\left(x+2\right)^2$

$N=\left(6x+2\right)\left(x-2\right)-\left(6x+12\right)^2$

$N=6x^2-12x+2x-4-36x^2-144x-144$

$N=-30x^2-154x-148$Câu trả lời: $E=\left(4-x\right)\left(x+4\right)-\left(x+2\right)^2$