Answer:
1.(x+2)(x+7)
First: (x)(x) =x²
Outside:(x)(7)=7x
Inside:(2)(x)=2x
Last:(2)(7)=14
Therefore,(x+2)(x+7)=x²+7x+2x+14
(x+2)(x+7)=x²+9x+14
2.(3x-2)(4x+1)
First: (3x)(4x)=12x²
Outside:(3x)(1)=3x
Inside:(-2)(4x)=-8x
Last:(-2)(1)=-2
Therefore,(3x-2)(4x+1)=12x²+3x+(-8x)+(-2)
(3x-2)(4x+1)=12x²-5x-2
3.(x²+4)(2x-1)
First: (x²)(2x)=2x³
Outside:(x²)(-1)=-x²
Inside:(4)(2x)=8x
Last:(4)(-1)=-4
Therefore,(x²+4)(2x-1)=2x³+(-x²)+8x+(-4)
(x²+4)(2x-1)=2x³-x²+8x-4
4.(7x-8y)(3x+5y)
First: (7x)(3x)=21x²
Outside:(7x)(5y)=35xy
Inside:(-8y)(3x)=-24xy
Last:(-8y)(5y)=-40y²
Therefore,(7x-8y)(3x+5y)=21x²+35xy+(-24xy)+(-40y²)
(7x-8y)(3x+5y)=21x²+11xy-40y²
