Question

помогите решить

(х + 3)(х – 7) - 4х(5 – 2х)

(a + 2)(a – 6) + (a+ 3)(a- 4)

(х –3)(3х+ 1) – (2х + 3)(4х – 1)

Answer 1

$(x+3)(x-7)-4x(5-2x)=x^2-7x+3x-3*7-(4*5x-4*2xx)=x^2-4x-21-(20x-8x^2)=x^2-4x-21-20x+8x^2=9x^2-24x-21$

$(a+2)(a-6)+(a+3)(a-4)=a^2-6a+2a-2*6+a^2-4a+3a-3*4=2a^2-5a-12-12=2a^2-5a-24$

$(x-3)(3x+1)-(2x+3)(4x-1)=3x^2+x-9x-3-(8x^2-2x+12x-3)=3x^2-8x-3-8x^2+2x-12x+3=-5x^2-18x+0=-5x^2-18x$