Đáp án+Giải thích các bước giải:
`a_1) M=(2a+3)(2a-3)(44^2+9)-(a^2-5)(a^2-5)`
`= (4a^2-9).1945-(a^4-10a^2+25)`
`=7780a^2-17505-a^4+10a^2-25`
`= -a^4 +7790a^2-17530`
`a_2) M=(2a+3)(2a-3)(4a^2+9)-(a^2-5)(a^2-5)`
`=(4a^2-9)(4a^2+9)-(a^4-10a^2+25)`
`= 16a^4-81-a^4+10a^2-25`
`= 15a^4+10a^2-106`
`b) N=(x^2+3x+1)^2+2(x^2+3x+1)(3-x-x^2)+(3-x-x^2)^2`
`= [(x^2+3x+1)+(3-x-x^2)]^2`
`=(x^2+3x+1+3-x-x^2)^2`
`=(2x+4)^2`
`= 4x^2+16x+16`
`c) 5(2x-1)^2+4(x-1)(x+3)-2(5-3x)^2`
`=5(4x^2-4x+1)+4(x^2+3x-x-3)-2(25-30x+9x^2)`
`=20x^2-20x+5+4x^2+12x-4x-12-50+60x-18x^2`
`=6x^2+48x-57`
