(а+2)(a-3)-(a+4)(a-7)=(a²-3a+2a-6)-(a²-7a+4a-28)=a²-3a+2a-6-a²+7a-4a+28=2a+22
При а=-1/2
2×(-1/2)+22=-1+22=21
Ответ:21
Ответ
@#@#@#@#@#@#@#@#@#@#@#@
=5а(а²-3аb+4b²)
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5х-2х= - 4-5
3х=-9
х=-9:3
<span>х=-3</span>
1) 120/100*40=48
2) <span>17.39:(15-14.26)-6:12.5=17.39:0.74-6:12.5=23.5-6:12.5=23.5-0.48=23.02</span>
<span>1. 15-14.26=0.74</span>
<span>2. 17.39:0.74=23.5</span>
<span>3. 6:12.5=0.48</span>
<span>4. 23.5-0.48=23.02
</span>